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Blender creates screenshot using python script but not when running in background
This question is just a stackoverflow copy since I've just figured a specific Blender Stack Exchange was existing ! Thanks for your help.
Am I crazy or is there some bug with this feature (using python script with blender running in background) ?
1/ Copy / paste the following code (from screenshot.py) inside Blender (switch to Scripting view) and it will take a screenshot but ...
2/ Call this script from command line : (so you can automatize screenshots while you're modifying the scene with your script(s) ... for your blog, a tutorial, etc.)
blender --background --python screenshot.py
And it will crash without giving informations about what is "incorrect" in the context
screenshot.py :
import os, sys

#FIXME: Blender creates screenshot using python but not when running in background
#
# Same result from Ubuntu stock version (2.76) and from ppa (2.78)
#
# Within Blender : unable to fix this last warning but screenshot is generated !
#
#Traceback (most recent call last):
#  File "/usr/share/blender/2.78/scripts/startup/bl_ui/space_text.py", line 32, in draw
#    text = st.text
#AttributeError: 'SpaceView3D' object has no attribute 'text'
#
# From command line (crash) : blender --background --python screenshot.py
# Unable to determine what's wrong in the context
#
#Traceback (most recent call last):
#(...)
#File "/usr/share/blender/2.78/scripts/modules/bpy/ops.py", line 187, in __call__
#    ret = op_call(self.idname_py(), C_dict, kw, C_exec, C_undo)
#RuntimeError: Operator bpy.ops.screen.screenshot.poll() failed, context is incorrect

def screenshot(P_filename, P_path = None):
  import bpy

  L_saveAs = P_filename
  L_saveAs = os.path.join(P_path, L_saveAs) if P_path else os.path.join("/tmp", L_saveAs)
  print("Scene saved in " + L_saveAs)

  #XXX: switching to 3D full view = maximize scene in main window
  #bpy.context.window.screen = bpy.data.screens['3D View Full']
  for window in bpy.context.window_manager.windows:
    screen = window.screen
    print("Window : " + str(window.width) + "x" + str(window.height) + ":" + str(window.x) + "," + str(window.y))
    print("Screen : " + str(screen.name) + ", Scene : " + str(screen.scene.name))
    #for area in bpy.context.screen.areas:
    for area in screen.areas:
      print("Area   : " + str(area.type))
      if area.type == 'VIEW_3D':
        for space in area.spaces:
          print("Space  : " + str(space.type))
          if space.type == 'VIEW_3D':
            #space.viewport_shade = 'RENDERED'
            for region in area.regions:
              print("Region  : " + str(region.type))
              if region.type == 'WINDOW':
                L_altBpyCtx = {                        # defining alternative context (allowing modifications without altering real one)
                  'area'      : area                   # our 3D View (first found)
                , 'blend_data': bpy.context.blend_data # just to suppress PyContext warning, doesn't seem to have any effect
                #, 'edit_text' : bpy.context.edit_text  # just to suppress PyContext warning, doesn't seem to have any effect
                , 'region'    : None                   # just to suppress PyContext warning, doesn't seem to have any effect
                #, 'scene'     : bpy.context.scene
                , 'scene'     : screen.scene
                , 'space'     : space
                , 'screen'    : window.screen
                #, 'window'    : bpy.context.window     # current window, could also copy context
                , 'window'    : window                 # current window, could also copy context
                }
                bpy.ops.screen.screenshot(L_altBpyCtx, filepath = L_saveAs, full = False)
                break #XXX: limit to the window of the 3D View
            break #XXX: limit to the corresponding space (3D View)
        break #XXX: limit to the first 3D View (area)

screenshot("screenshot.png", ".")

3/ By the way, call it without the --background argument and it will generate an empty screenshot (size of your window, full of default color, gray in my case). In the meantime, uncomment
#bpy.context.window.screen = bpy.data.screens['3D View Full']
and/or
#space.viewport_shade = 'RENDERED'
And you'll see your Blender interface being affected (switching layout of your views from 'Default' to '3D Full View' and/or your viewport shading from 'Solid', by default, to 'Rendered') ... so the script is actually interpreted but it does not generate the screenshot !
No matter what, the problem seems coming from calling Blender with "--python somescript.py" directly from the command line
I'm probably missing something ?! Thanks for your help

Got the answer from a Blender guy (thanks sergey). Bottom line : it's a limitation since all the scripts passed via command line argument are executed at command line processing time, prior to any OpenGL draw is done !

The warning is caused by script trying to trick the system and
  override the context, that context is likely in inconsistent state.
  When running screenshot from the interface you don't need to override
  any of the contexts.
All the scripts passed via command line argument are executed at
  command line processing time, prior to any OpenGL draw is done. The
  screenshot operator itself is just reading OpenGL buffer,m without
  doing any actual drawing (it can't draw anything since that'd be
  unsafe).
When running blender in background mode, there is no window created,
  which also means there is no OpenGL context. You can;t use screenshot
  in such configuration.
So thanks for the report, but it's just limitation which can not be
  easily bypassed.

Precision : (since the provided code do not show all the attempts made trying to "trick" Blender)
Sadly, if you are also / still interested in such feature, you'll have to think outside (Blender) box ! Don't waste your time trying to "trick" Blender, like delaying script execution, playing with application handlers, faking script import in a Text editor, etc. ... I've done it for you : it doesn't work, probably for a very similar reason.

surely that's the reason to have bg mode, not to have the UI overhead.

Yep, but do not help when you're trying to take a lot of screenshots of that UI (multiview, multiaxis, step-by-step) in a 3D printing context (programmatic modeling). Since this limitation is not only affecting bg mode but all scripts launched from command line

@AnotherTuxUser But how come it doesn't work when we don't use bg mode?


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How can I get my texture to appear correctly on my cylinder?
I am trying to make a simple casino chip.  I have the textures for the face and the sides created with photoshop. The texture on the face appears correctly, however, the texture on the side looks awful.  I just want there to be the same number of white stripes on the sides of the chip as there are on the top and in the same spots.  In other words, I want the stripes on the top to extend down the sides.  How can I accomplish this?  The cylinder in blender is 39mm in diameter and 3.9mm thick.  The texture in PS is 3.9mm wide by 39mm tall. This is what I have so far...

This is happening because each side face on your cylindrical chip is having the texture applied to it. What you want to do is UV unwrap the whole edge as one strip rather than having a bunch of overlapping faces. To do this you need to mark some seams to tell blender where to separate the mesh. Mark seam the top and bottom circles and then one vertical edge (You can do with by pressing Space and then searching for "Mark Seam").
It will look like this:

From here you should select your whole mesh with A and then press U to unwrap.
You final UV map should look like this:

Your chips top and bottom textures should be aligned with the circles and the side texture should go across all of the side faces.

Here's how I would go about texturing the chip. (I didn't have an actual texture off hand so I just threw together one really, really fast)

Basically what I did was I UV unwrapped by clicking "u" in edit mode with all the vertices selected then choosing smart uv unwrap. Uncheck "Stretch to UV bounds" so that the circles are not distorted. (If you want to you can then reorganize the UV Layout with the same shortcuts as in the 3d view with g to grab, ect.) Then save the UV layout by going to "UVs -> Export UV Layout". Bring that into photoshop or another software that supports layers. Align your texture to the layout and save your texture (don't forget to turn of the UV layout layer so you don't get black lines in your material). Next go to your node editor and copy how it is in the image and choose your texture for the image texture node.
Edit: Oh, I misinterpreted how you wanted the stripes. Instead of doing the lines straight down like I did, You'll have to click on the vertices in the UV editor to find the faces that the stripes are supposed to be on and color them based on what faces you found.

The simplest way to do it would be:
1 select your chip
2 Press U
3 Select 'project from view' from top angle
I think that will give you the desired result.

This only works for the top and bottom faces. It does not fix his problem. The side face data would end up compressed into a line.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


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How to use Blender to get model to a state where it can be shrank with gltfjsx
I'm fairly new to Blender (and trying to understand how to use 3d tooling in general), so this question is coming from still trying to 'map out the landscape' to use a visual analogy.
I'm trying to run this command:
npx gltfjsx ./myfile.gltf --types --shadows --transform --aggressive --draco https://www.gstatic.com/draco/versioned/decoders/1.4.1/
which usually compresses files with no issues..
If these files are scans generated by lidar scan, (or the other algorithmic method which uses photos, for which I forget the name), I get this error:
Error: maxMemoryUsageInMB limit exceeded by at least 225MB
I thought for a while that it was because these methods produce a lot of polgyons, but after a bit of research, I'm wondering if it is because of the texture sizes, and whether or not it is possible to shrink them (https://github.com/donmccurdy/glTF-Transform/issues/344)
Would really appreciate knowing if I'm following the right lead here, and if so, where would be good to read next.
Thanks

I'm struggling to work out what this has to do with Blender!

Maybe I need to move the question to a different stack exchange community. I know blender can probably be used to reduce texture sizes, but I'm not sure if that is something which causes an 'unpegging' with the polygons (or is that just when merging polygons?) Ideally, if someone knew what I need to google in order to figure out how to change texture sizes (and indeed if this is the the right way to go about this), then this would be ideal. Thanks for the help @JohnEason

I've posted an update on glTF-Transform#344 you can reply there if you like. GitHub discussions for glTF-Transform or GLTFJSX might also be good options. The limitation here is indeed the size of the textures. Blender can resize textures, but may not be the easiest way to go about this.

Thanks again @DonMcCurdy, saving as a non-embedded gltf and resizing manually should have been something I thought of, seems so obvious now!

Thanks to @donmccurdy for the help with this (https://github.com/donmccurdy/glTF-Transform/issues/344).
Steps are as follows:

Use blender to save a HUGE gltf as a 'separate' file (so the texture is separate).
Use Photoshop/Gimp to resize the texture.
Re-import into blender
Export again as an embedded gltf
Run npx gltfjsx ./myfile.gltf --types --shadows --transform --aggressive --draco https://www.gstatic.com/draco/versioned/decoders/1.4.1/ to squish it into a nicely sized glb file

(When you do 5., the tsx generated might include a . in the file name, so either rename them in blender in step 3., or write typescript like so in the generated tsx):
type GLTFResult = GLTF & {
  nodes: {
    Mesh_0001: THREE.Mesh
  }
  materials: {
    'material_0.001': THREE.MeshBasicMaterial
  }
}

<mesh castShadow receiveShadow geometry={nodes.Mesh_0001.geometry} material={materials['material_0.001']} />
```

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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How do gltf properties (such as material and geometry) map on to what is exported by blender?
When I export a blender object as a GLTF file (and then import into a web app), I'm not completely sure as to how the object properties are mapped..
For example, I would usually export an object, and everything needed would be under the material and geometry properties (within the gltf object).
The other day, I combined a few objects into one (as per here), however, noticed that there were no 'material' and 'geometry' properties on the exported object.
I'm still pretty new to blender, so maybe this is quite an obvious question, but any help would be appreciated. Thanks.

As a side note, 'materials' IS selected as per here: https://blender.stackexchange.com/questions/200840/glb-gltf-export-how-to-include-color-material-information

You can see what the exporter expects materials to look like in the manual. A more concrete question would be easier to answer.

ah so apparently it is 3 textures that I need to merge (the newly combined object has 3 textures/shaders attached after the merge). I tried this: https://blender.stackexchange.com/questions/32677/how-to-combine-two-different-textures-into-one but it isn't really the right thing

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Exporting a textured image from Blender and using with React Three FIber (shaders?)
I'm still pretty new to 3d with blender (and coding in 3d), but I'm trying to create and export a material using nodes (instead of a jpg image):

In React, I'm coding as follows:
export default function Ring({ ...props }: JSX.IntrinsicElements['group']) {
  const group = useRef<THREE.Group>(null)
  const { nodes, materials } = useGLTF('../assets/ring.glb', 'https://www.gstatic.com/draco/versioned/decoders/1.4.1/') as GLTFResult
  return (
    <group ref={group} {...props} dispose={null}>
      <mesh castShadow receiveShadow geometry={nodes.ring.geometry} material={materials['Material.001']} />
    </group>
  )
}

However, in the browser I am getting this result:

I'm trying to figure out if the issue is:

a. There is nothing to reflect, and therefore no color (I added <Sky .. /> and <Environment .. /> tags hoping this would solve it.
b. The code needs some extra code to pull in other parameters which are part of the object itself:

c. I need to add extra shaders or something because of 'unknown unknowns' in the way I'm using things.
d. I've exported it wrongly - which might be the case because I've tried importing here: https://3dviewer.net/ and it is still white. (I tried using 'apply modifiers' when exporting).

Either way, I need to figure out if this is an exporting issue, or a coding issue.
Thanks for the help.

Generally speaking there are limitations exporting node-based materials from Blender. See https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures

tl;dr — to export to glTF, use a Principled BSDF material. Details on how to set up your materials for export are included in the addon documentation.


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Keep Mirror Sides Bridged?
When I use the Mirror modifier and move vertices away from the "mirror," the top "face" splits, making a large hole between the faces. Filling the hole voluntarily is quite annoying.

Mirrored...

Faces Split.
Is there any way to fix this problem? I don't see it happening with any other user on BSE.

Is the "clipping" option on the modifier the behavior you are looking for? Or are you after something else?

Note that the two later-mentioned options are not checked because this photo is a cropped version of one that came from the Blender Reference Manual.
You need the Merge option. Clipping, too, would help.
Merge
The Merge option will join two vertices (1 real and 1 generated by the Mirror modifier) into one. The two to be joined are specified by each  being within the Merge Limit: of each other. 0.001 is a good default value, so I would leave it there.
Clipping
This prevents real vertices from breaking the "mirror." This will make joining the vertices a lot easier because you can just grab the top 8 faces (in your case), key G, then Y, then slide your mouse left to bring the sides together and LMB to confirm when the vertices stop moving as they hit the "mirror." The bolded part shows how Clipping factors into merging the vertices.
Last Note
Do keep in mind that once you enable this and merge the vertices, you will not be able to move them away from the mirror for the following reasons.

Think of it like constraints. A "merge" constraint merges the vertices into one; they can no longer be separated.
A "clipping" constraint (for some reason) still treats the vertices as two. Moving either away from the mirror would pull its partner through. That can never happen.

If you want to move a joined vertex away, turn off Clipping.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Fire does not show in final render
I made a campfire, but when I render it the fire does not show in the rendered image. I've put all the textures and the .blend in a Google Drive link.
Thank you,
Andrew

Were you hoping for something more like the following (frame 8)?

If you were, you needed to change the material, Material, from a Transparent BSDF to the following node setup. This is pulled from the Vfx Blender's YouTube video, How to kick a Fireball (blender tutorial) [HD] part 1.
As I understand it, it uses the Attribute nodes to determine what part of the cube's volume is smoke and what is fire. The ColorRamp obviously colors the fire, and the Math > Multiply node set to 9.000 determines how transparent the fire is (0 being clear). The Math > Multiply node set to 7.500 determines how transparent the smoke is (0 being clear).

Here is the adjusted .blend file (w/o textures because they didn't come through Google Drive):

@AJ.vdw200 If my answer helped, please consider marking it as accepted by selecting the check mark in its upper, left-hand corner. It would help me greatly and make me very happy!


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Tracking moving points on a reconstructed plane
I would like to track animals moving on a plane from an aerial video. I'm very new to Blender, but believe that there is a way to do this. Up until now, I have managed to solve the camera motion from tracked points on the ground, and reconstructed the plane on which the animals are moving - this is set as the Floor of the scene, since it really is just a plane. Now I would like to track the animals - they are small in the footage, so every animal can be tracked by one marker.
My question is as follows: Can I tell somehow Blender that the animal object is located on the floor, and thus, can I solve its motion from only one track?

Information Download
When you have a point that you have tracked in the Movie Clip Editor, you generally use it to solve camera motion. Occasionally, like in a VFX scenario, one might deploy a style called Two-point Motion Tracking. This uses two tracked points, reconstructed as empties that will move on an X/Y Plane. In the linked video, the narrator goes on to show that if you have a dowel rod with sharpie at the top and bottom (points for tracking), and you track those points, you can stretch a glowing cylinder between them and make it look like the person is wielding a lightsaber.
Your Scenario
In your case, you will probably be looking at a type of One-point Motion Tracking, except with multiple one points for each scenario.

You will want to be happy with your camera track. After tracking the animals, re-solving the camera motion will be a pain to not possible.
Track an animal.
Go to Bottom toolbar > Reconstruction menu > Link Empty to Track. There should now be a Plain Axes Empty connected to the Camera by a dotted blue line.
In the 3D Viewport, switch to Local Transform Orientation.
Move the Empty as close or as far away from the camera as needed (probably along Local Z).
Parent your animal (I assume) to the Empty.

Hope this helps and happy Blending!

It helped, thanks! :) Now the marker of the tracked animal appears on the 3D viewport, and moves more or less on the Floor plane. Is it possible to fix the Empty to the Floor, because I think that the distance between the Empty and Camera are fixed now, and - since the height of the camera changes slightly - the Empty goes sometimes below the plane and sometimes above a bit.

@KatalinOzogany Glad to help! If you liked my answer, please consider accepting it by selecting the checkmark in its upper, left-hand corner. It would help me greatly and make me very happy!

Is it possible to fix the Empty to the Floor? The height of the camera changes slightly, and the Empty goes sometimes below the plane and sometimes above a bit, since the distance of the Empty and the Camera are fixed.

@KatalinOzogany You could go to the Properties panel > Object Constraints tab > Follow Track constraint and click Constraint to F-Curve. Then, to to a frame in the Timeline where you like the Z-Axis Position of the empty in question. After that, key N to toggle open/close the 3D Viewport Properties Panel and go to the Transform tab. Right click on the Z: Location Field and choose Clear Single Keyframes.

@KatalinOzogany Glad to help!


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Merging Multiple Textures on a Single Model into one Mega-Texture?
Every time I try to search for an answer or solution to this problem, it always comes up with the wrong information or something that is so outlandish that I don't understand.
I'm relatively new to Blender and I have a 3D model I downloaded that has a multitude of textures, from eyes, mouth, and body. I want to merge all these textures into one image so there can only be one texture file associated with it.
How can I do this? Do I need to compile the images in the UV/Image Editor, then re-UVmap the images in Blender? If so, could I just copy existing maps and somehow paste them onto the compiled version? Is there a wizard or file format that can do this for me?
Thank you for any help and I'm sincerely appreciative of any assistance.

Look into baking.

Ah, that was actually what I was looking for. Sorry for the thread, and this is resolved! Thanks.

If my answer helped, please consider accepting it by selecting the checkmark in its upper, left-hand corner. It would help me greatly and make me very happy! Thanks.

So to write up an answer, the OP needed baking.
Cycles baking is a relatively simple process as far as Blender goes, and is roughly like the following:

UV Unwrap a mesh with no overlapping Islands.
Add a new, blank image in the UV/Image Editor.

Go to the Node Editor and add an Image Texture node. Select the blank image. Do not make the image interact with the node tree in any way. Make sure the node is selected.
Go to the Properties panel > Render tab > Bake dropdown and select the following settings (for pure image textures).

You will then have an image with all the various Image Textures mapped onto it. You can incorporate this image with UV Texture Coordinates into one mega-object material.

Hi. I've recently come across the same problem as the OP. I have an OBJ+MTL with some PNG textures. I want to merge these PNG textures into one. Doing as instructed in your answer, the first step (UV unwrap) totally messed up the UV mappings of the original textures. I am not sure if it is because Blender is different from 4 years ago when it comes to baking. What should I do?


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Can't see animation after exporting to video

I started using Blender a few days ago...
For some reason, after I rendered the animation to a video file, I was left with this grid (see screenshot). How do I go back to the 3D Viewport where I can edit the animation? The wierd thing is that I can see the camera's perspective just fine in the upper right. (I'm using Blender 2.77a)

Hover your cursor over the grid and key Esc until the grid goes away (probably twice).
What has happened is that because you selected Image Editor in the Properties panel > Render tab > Render dropdown, your computer rendered your video by switching the screen that was previously there (a 3D Viewport) to a UV/Image Editor.
I generally select New Window, because then you can simply X out of the window once it is done.

Wow, thanks! I spent nearly 30 minutes trying to figure out what I did wrong.

@0-60FPS glad to help!


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Cloth colliding through mesh?
Sorry for asking so many questions about this one project, I'm sure many of you have seen it a lot already. This should be the last one for this :P Thank you all for helping so much already !
Anyways, I'm almost done my little project, here it is in it's current state:

Everything goes pretty well-- except the pants, as is evident.
Here is the blend:

The pants have a cloth modifier on them with the Quality slider turned up to max (as that helped with this issue previously when the pants were at rest. Not the case right now). I've tried playing with the presets to no avail. The pants are pinned at the waist and ankle through pinning via a vertex group. The pants are also parented to the character to keep their offsets to it.
How can I fix the melding issues with the pants?
Edit: Tried removing the cloth modifier, but the leg still doesnt seem to collide with the body despite both having collision physics... Hrm.
Edit: Tried turning up quality on collision, no improvement :(

I spotted one of the problem was that you didn't apply the mirror modifier(try checking that out in edit mode), there are two pants on that guy, and try pinning some more vertices around the legs to give a bit more of control to follow the legs. Hope it helps! and by the way why don't you try generating a rig thought it is comparably simple model that you're doing.

Thanks for spotting those two obvious issues >.< I applied mirror, removed the extra mirror on the pants and added some more pin vertices on the pants-- however... not a lot of progress :(

should the the cloth be simulated as a soft body? if not, you would always weight paint to make it follow the mesh.

Ok, I just did a simpler rig now the answer is which is not very certain that I could only figure out there must be something wrong with how you adjusted the armature and the pinned vertices most probably won't move so the leg that's kicking is something you need to unpin like:

make sure you enable the cloth simulation on the physics tab ONLY FOR THE CLOTH(PANTS) and the collision set only for the mesh. and hence the result:

(this is a simpler rig though.)

I have removed the pinned vertices on the kicking leg, removed all physics, added collision to the character, cloth to the pants, and turned quality to max...
And still the problem persists :/ Is my rig the issue? Im not understanding why you can get clean results for what Im doing and I can't

Can I have that blend file so I can see the differences? :o

Figured out the issue.

Well what was the issue, sorry I couldn't provide the .blend

On the character I put the armature modifier before the collision modifier. Switched them around, 90% of poke through went away >.< Well that was easy. Still have a bit to go but its bearable now.


text:
Converting a masked 2d grayscale image to an object
I want to achieve the following:

At the moment I can do it, by using Shapeway's 2D to 3D image converter, download the result as X3DB, then use NetFabb Basic to convert it to STL, which I can then import to Blender. This process although works, I would like to do the whole process using Blender in order to not rely on web tools and to have more control on the result.
I've been trying to mix landscape topography with extruded curves the following ways:
Option A.

Create an SVG outline of the image
Import the SVG, and convert it to a mesh
Use the displacement modifier to modify the mesh using the original grayscale image

Option B.

Create an SVG outline of the image
Import the SVG, and convert it to a mesh
Create a plane, use subdivide to add more vertices
Do a boolean cut to change the shape of the plane to the outline of the image
Add a displacement modifier to modify the resulting mesh

In neither case did I get anything useful, the usual results are:

A mesh with tons of huge spikes (which of course doesn't resemble what I want)
A mesh with only a few spikes (which still doens't look anything like what I want)
The mesh dissappears completely
Blender crashes

Any ideas?
Edit:

I already have the SVG version of the outline. I can also generate an SVG version of the grayscale image as well, but I don't think that's necessary. I'm using Illustrator btw.
I don't need an automated way (yet, hopefully I can script it once I know how to do it manually), my problem is that I can't even get the mesh created manually in any way.
As this is for 3D printing both the outline and the topology are important (the depths of the ridges are not always equal everywhere. Also a generic solution would help me in generating other types of pendants and would also allow me to add smaller details).
Here is the end result I would like to accomplish from another angle for reference (this is based on the mesh generated by the shapeways' tool, and it also contains a mirroring):

Does this help? http://blender.stackexchange.com/questions/1609/tracing-a-monochrome-image-into-a-3d-extruded-object-with-a-script/1610#1610

@RayMairlot I already have the SVG outline of the image

Unless you want a single mesh merged version the SVG traced version is all you need. Don't convert it to mesh. Just use the built in curve tools to extrude and bevel the logo. Add a copy of the curve bellow it and remove everything but the outline spline to make the solid "background fill"

@root This is for 3D printing, so topology is actually more important than the outline, but of course both of them are necessary. I can do one or the another, but I need both. See the example image above, it contains both the topology and the outline. Also, I don't need an automated way (although it would be good), at the moment I can't even get it working manually in any way I try.

@DuarteFarrajotaRamos unfortunately that wouldn't copy over the topology from the grayscale image. Of course I could do the topology transformation in blender to create the pendant shape, but I'm more comfortable doing it in Illustrator

http://blender.stackexchange.com/questions/51792/how-can-i-model-gothic-style-windows/51884#51884

@eromod that does look similar to what I want to achieve, let me try it

I used your image as height map and got this result:

Work in progress:

Take a plane and scale it up, subdivide it ~1000 times.
Add a displacement modifier with the image as texture.
To smooth out the result, add a subdivision surface modifier before and after the displacement modifier.
Apply the modifiers.
Go into edit mode (be careful with your modifiers, the first time Blender crashed at this step due to too many polygons) and select all the mesh. Go to "smooth vertex" and smooth it a lot (5 times with factor 1 on the screenshot; should have been more)
Add a decimate modifier to remove unnecessary geometry. Remove vertices based on the angle with the "planar" mode. I had to first decimate it with "collapse" because planar decimation takes a lot more of time to calculate. Ratio 0.1 and 6° angle limit worked well.
Go into edit mode again, select all vertices on the bottom with height 0 and delete them.


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Rendered file black, even though Play Rendered Animation is correct
I downloaded a Blender intro template. I rendered it and it saved. I went to open the file, but the video is all black and only the music is playing. I looked at the Blender Play Rendered Animation (Ctrl + F11) and it was fine; with video. Please help.

When you render the file you must choose the output format and the video codecs. Probably your video player is not supporting the video codec that has been rendered.


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Bliniking shadow on rendering result
I am making walking robot and get a weird blinking shadow on the robot's body.
This shadow lasts only one frame and then disappears.
Blender: 2.77
Renderer: BI

Frame 3 is similar to 1st (without shadow).
If any details help to fix this just ask.
I don't know what information might be useful for it.
Response to Sonace:
It doesn't help.

And the robot doesn't have any duplicates under its body.

Welcome to the Blender.SE. Is the mesh animated ? Is the topology of the mesh good enough, so could it be z-fighting ? Also do you use Motion Blur ? (if yes try disabling)

do you use smooth or flat shader?

Mesh animated (robot body moving to camera while robot making his 1st steps)

Smooth shaders does not fix artefacts.
https://i.sstatic.net/MhcSQ.png

I don't know is topology good or not. Is this screenshot can help to understand it? https://i.sstatic.net/X0iWs.png

And motion blur is disabled

Have you checked for overlaping faces?

Checked. In extreme way. I have 1(removed front face), checked that no other faces present and 2(recreate face again).
3(render result)

It's magic! It's working! :-) cleanup fix everything, thank you!
https://i.sstatic.net/SxiKE.png

@cegaton Oops, sorry. It's not magic :-( cleanup helps a lot, but doesn't fix all blinkings :-(
It's much better, but sometimes still blinking https://i.sstatic.net/nhf5o.png

This is in blender render correct? Also do you use a point lamp to light the robot?

@xlxs scene rendered correct, except this blinking.
I have only one "sun" lamp on scene

Well since nothing works im posting something that may work. sellect the object you have this problem apply a smooth shader in it and then add a subdivision modifier change it to simple from catmull-clark.Then change subdivisions to something big like 4-5.
And check again to see if it works.If this still doesnt work add one more subdivision modifier but not simple this time.And check again.
This wont work for sure*

smooth + subdivision helps to fix it  https://i.sstatic.net/7rrJC.png

@Mike Glad it worked :)

Go to edit mode, click 'Remove Doubles' (if there are some, it causes z-fighting) then go to Shading / UVs and recalculate.
If it dosn't work there is a duplicate under the object. Remove it.

It doesn't help.
and robot doesn't have any duplicates under his body

@Mike I edited your question with the links.

@Sonace See my edit to the question.


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How can I use the Subsurf Modifier on a curved surface?
I'm trying to create a smooth, convex surface. The Subdivision Surface modifier gives an erratic result, and I can't control it even with the Edge Crease.

Have you tried inserting another edgeloop to the left of the problem area. It will be easier to answer if we had your mesh. I suggest isolating the problem area (deleting everything else) and uploading it to http://blend-exchange.giantcowfilms.com/

Subsurf isn't working well with tris. Make this triangle are to quad and add some loop cuts as @Leander suggest.

It seems you have inner faces (visible in the top left of the second image). Probably you need to remove them.


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Which one of these clips would track the best?
So I recorded some clips at my school. They are all in my Google Drive.
I'm pretty new to tracking in Blender; I have used Adobe AfterEffect's wonderful 3D Camera Tracker in the past. I would like to ask the experienced trackers on this website which of the above linked clips looks like they would track the best. I'm trying to recreate this effect as a final product.

This will be a great question to have on the site, if we can get a good, thorough answer with generic application.

I disagree that he's asking for an opinion. It sounds like he's asking for guidance on how to identify a suitable candidate for tracking. But yeah, one question per post.

cegaton has it http://blender.stackexchange.com/questions/42329/how-can-i-get-better-results-when-doing-camera-motion-tracking

How do I accept a comment as an answer? I'll delete this comment afterwards, I'm just not sure. @cegaton


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How can I create a realistic stack of pages?
I'm really new to blender and one thing that I'm finding difficult is how to create pages on a notepad so when it is viewed from the side you can clearly see pages and image bleed (see picture in link).
I tried duplicating the plane 50 times but it didn't look good so I chose to extrude the plane to the final height of the notepad but now I can't figure out a way to split the sides so they look like they are pages.
This is what I want it to look like (more images here):

Any help would be greatly appreciated as I'm struggling to find a way to do this.
Thank you

http://blender.stackexchange.com/questions/55372/how-to-model-spread-book-interior/55404#55404

You can uv unwrap your volume/pad from the top with project from view, so that you will have the yellow colors bleeding along the sides as in your reference, as long as you keep the UV inside the texture. Then you can use a normal input combined to a dot node to separate the vertical sides and the top face and use this output to create a variation of the texture (adding some vertically compressed noise for page division, multiplied to the image texture and a bit desaturated). This texture is then plugged into a basic diff+glossy mixed shader. Big advantages here, you are sure the colors on the side are in good position regards to the top, and you can change the whole thing by tuning the uv or changing the texture !

Blend is here

Improved the answer, and I think the question is not really a duplicate as it has been marked, as the answers in the duplicate question are not taking into account the bleeding of the colors on the sides of the stack of pages, which seem problematic for the poster.


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Shape keys and Drivers problem

[

My drivers are not working correctly with my shape keys everytime i try to make a shape key work with an objects Z Axis i have to have it way beyond the mesh,I have already tried using the generator but that did not help.
how do i only have to make it so that i only have to move it up slightly.
I also have my shape keys needing the object to the go the opposite direction of where it was intended to go

Did my answer not fix your problem?

What kind of scale do you have on that model.  Shapekeys (unless defined otherwise) generally have values from 0 (off) to 1 (fully on).   The value -6.7 will map to 0, in which  case will do nothing.  The value -6.7 is showing that your mouth top  cube's location z  is 6.7 blender units below its (0, 0, 0)  position.  If you want to map say [-8, 8] to [0, 1]  use something like (var + 8) / 16 as your driver expression.

i tried that and now it has to go under the whole mesh to work also since its the top mouth i want to go up to open the mouth and down to open the bottom of the mouth

Post the blend.

Added .blend file

To increase the effect of, and invert the direction that effects the shape key in your driver:

Go to File->User Preferences.
In the User Preferences window, select the File tab and check the box for "Auto Run Python Scripts".

Go to the graph editor in the Drivers tab and Change the type to "Scripted Expression".
In the expression box, type "-2 * var" (no quotes and with var being your variable name).

This expression will multiply the distance you target object travels by 2(or whatever you number you choose). So your target will have to move half as far. The higher the number, the shorter the distance. Making the number negative changes the direction it must travel.
EDIT
After looking at the blend, the target is upside down on the Z axis, making its local space z axis(and your variable) -6.69. Negate that by adding 6.69 to it. Then multiply that by -10 so you will only have to move up by 0.1 to reach the maximum of the driver. So the expression is: -10 * (var + 6.69) And make sure "Auto Run Python Scripts" is enabled.

didn't work for me

What was the result. What was still "wrong"? If you can be more specific I can help you.

it seemed to be working somewhat before but instead of dividing 2 i apparently had to multiply it by over 100 and as i kept going it just stoped changing the value

Looked at the blend. Please see my edit in the answer.

it still going in the wrong direction

You want to drag it down to make the lip go up? change the -10 to 10.


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Weird Tears in terrain mesh in Render View only
I used a LIDAR point cloud, imported it in meshlab, sampled (from 9 million points to about 1) and reconstructed a mesh for it, set normals, exported as OBJ, then imported it into Blender 2.76.
I have Cycles Rendering on, made a simple material in the node editor with just a Diffuse BDSF shader with a flat color and no roughness (0.1 roughness looks the same).
I get this wierd result:

This is in Render View

Material view looks fine.
What am I doing wrong?
Here is my .blend

Looks like either z-fighting or messed up normals.  Try [W] > Remove Doubles.

Remove doubles didn't do anything. While I did find some messed up normals, there's very few of them (only in face, not in vertex or edge), and generally are nowhere near the problem areas, which are ubiquitous. These "tears" aren't even in the same shape as the triangles which make up the surface. Selecting the faces under these black tears and flipping normals does not eliminate them. Most normal or meshing errors I've found and corrected don't present themselves like these artifacts at all, and any manipulation to amount of vertexes, overlapped lines, etc do not help.

Does it still give these artifacts when actually rendered (not just in render view)?

It does still have them when actually rendered.

@PGmath I still haven't found an answer for this.

It would help to have the .blend file to look at.  Try uploading it to Blend Exchange and editing the given link into your question.

@PGmath I've added the .blend file. Had to trim it a bit since it has a lot of points and was over 50mb, but the result is the same.

Wow, I've never seen anything like that before.  There is something really really messed up about the normals on that plane.  I'll have to check it out on my workstation as it's running way too slow on my tablet.

The problem is caused by the fact that although the terrain origin is at (0,0,0), the real mesh is still very far from it.
So it seems you have to use a very large clipping range (1000000 in your case), which allows you to see objects, but reduces the depth precision. This is a known limitation of all softwares using OpenGL.
To fix it, you can:

Increase the start clipping.
Decrease the end clipping.

However, you may also have to scale the objects to see it again. (And, in your case, I would suggest you select the terrain then ShiftCtrlAltC > Origin to Geometry, to relocate the origin from afar. Then move them back to the world center.)


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Scale and dimensions problem importing to Unity
I'm trying to import a simple plane mesh into Unity (to generate some map)
I have my simple plane that I want scale to be 1x1x1 and dimensions 50x50 but whatever I do; change dimensions scale changes i cannot make it align perfectly in Unity.
If i can align one edge; the other is not perfectly aligned.
I'm exporting as .blend file.
I've tried the following answer :How to align a cluster of points?
But i can't make all my points 'z to be 0; why ?
What am i missing here ?

Could you clarify, what's your main question ? About making the plane's dimensions 5050 and scale 11*1 ? Or to scale all the vertices of the plane by Z axis so the plane would be flat ?

you should edit the title, this has nothing to do with Unity.

From your question your trying to do 3 things at once. maybe some of these tips will help.
To keep the scale at 1,1,1  make your changes in Edit Mode, not Object Mode.
If your object is not scaled to 1,1,1 you can reset this with:
'Apply Scale'. 'ctrl+A -> scale'
To make your plane flat, select all the vertices and scale them on the Z to zero.
Same to align any row of vertices, select the row, and scale X to 0.
To put the plane at the Global Position z=0, Set your 3d cursor, and then snap the plane to it.


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Blender export support for 3MF (or AMF) file format?
As I am preparing some design to be printed on a full colour 3D-printer, I ran into the 3MF file format as a possible format supporting colour better than .STL.
see: http://www.3mf.io/what-is-3mf/,
see: also: https://stackoverflow.com/questions/20583998/info-about-3mf-file-format-for-3d-printing)
On the website there is also a link to an "Open Source Library": https://github.com/3mfconsortium, I didn't go into details (and I didn't check the Microsoft side (is their Open Source same as ours?)), but support for export to this format from Blender would be nice, i.m.h.o.
What about support from Blender to export in 3MF ? Can somebody shed light on this?
Thanks for reading and responding in advance!
Regards,
Wim.

Only thing I could find http://blenderartists.org/forum/showthread.php?382248-standalone-Python-Microsoft-3mf-to-Blender-usable-ply

Hi Duarte, Yes, I saw that one, but I run into the same error as the person who replied on this, it complaints on "colorid".

This is a tough one. My concern about most of the answers that I see on the Blender forums is that people don't get that 3MF is NOT like STL, it allows for actual bitmaps for textures, not just one flat color.
So, I do have a workflow for you, that will at least get your model out, if you are running Windows 10.
Setup Blender to export to GLTF. Export a binary GLTF (GLB).
Open the Windows 3D builder app. It's free.
Open the GLTF with 3D Builder.
Then export a 3MF.
I tested it with Simplify3D and it seemed to work fine. The model sliced fairly easily.
    == John ==


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Timebase error when encoding
I am using Blender's Video Sequence Editor and it won't let me render it. The error message...

Timebase 20999/500000 not supported by MPEG 4 standard, the maximum admitted value for the Timebase denominator is 65535

...keeps popping up. I don't know what to do. It also won't let me save it either. Here are some screenshots.

Please do not post duplicate questions like this.

Frames Per Second
The output file format you've chosen, Xvid, does not support the frame rate you've chosen. Your error,

Timebase 20999/500000 not supported by MPEG 4 standard, the maximum admitted value for the Timebase denominator is 65535

basically says: your frame rate (5 frames per second with a framerate base of 0.210, totaling 23.81 fps) isn't compatible with your output file format.
How to fix
As far as I'm aware you can't fix it, you have to either change the fps or the output file format.
Happy Blendering!

Just curious: why do you need a video with exactly 23.81 fps?
You might need to export your animation as an image sequence, and later use some external video encoding software to create a video with that special frame rate.
I tried using a Quicktime with MPEG-4 codec and it worked.


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Limited options in a certain area?
Ok so i am a bit of a noob in blender, so I need help with this.
I am trying to texture something, but there is no texture button where there should be, because the blender edge window cuts it off
here's a picture

You have to hover over it, and then scroll up and down

You have two options:

Hover your cursor over the buttons, press Mouse Scroll and drag it left/right
Place the cursor on the window edge and expand the panel with LMB

Mouse over the strip that is pictured and use your mouse's scroll wheel. You can also resize the Properties panel window. You can read more about resizing view windows in How to close view windows?
Resize window shown first; then scrolling:

Either resize the window if you have the available screen space for it, or use the middle mouse button over the header to scroll the tabs


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Why are there no shadows on the ground?
I am new to Blender and am having some trouble with shadows. I am making an image and I have positioned my camera and models, but when I render, there are no shadows on the ground

Please help me as shadows will give my project a more professional look.
Thanks.

Here is my setup

Whoops Here is the setup :https://drive.google.com/open?id=0B8lMs9Yq18T7MXE1MlpuUkU0WVk

I do not know what render engine is and what i am using. If you could please inform me about that

You appear to be using Blender internal renderer. There are no shadows on the ground because there is no ground to cast shadows on. If you want shadows create a ground object first.

How do i add a ground?

Do i just use a pane?

Yes, just Shift + A to add a plane.


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How to switch between cameras?
I just started with the BGE and am making a 2D mario-type scroller game. The level is long enough to require two cameras, so I made an invisible plane which on collision switches to the sexing camera. However, I also want to go back to the first camera. How do I switch back?

@ShadyPuck Regarding edits, just worth noting that edits should be substantial, see: http://meta.blender.stackexchange.com/a/242/241

I have seen it. Most edits that I do are substantial. @RayMairlot

Stateless solution
I suggest to do the exact same thing.
So you get:

logic to switch from A to B
logic to switch from B to A

Ensure to avoid triggering both at the same time. e.g. have a according difference between the collision objects.

Python solution
Since this a general question about changing the camera in the BGE, I'd like to throw in a method using Python. The following screenshot shows an example where the camera is switched when the spacebar is pressed. It involves:

two cameras (cObserver and cFollow)
an object (LOGIC) carrying the script (nextCam)
a script containing the camera list and simple logic

Think of a racing game with several cockpit-, follow- or even spectatorviews with keyframed camerashakes.
I personally prefer this method when the number of cameras increases, since it's easier to maintain than logic bricks. Additionally you can run additional logic depending on the active view, like changing the zoom level of the active cam with KX_Camera.lens.

you could try to incorporate a property to go along with the plane. For example when your character hits the plane and the property is 0 set camera to camera1 then when character hits plane and property is 1 set camera to camera0
link to download blend
click

I did that but if I add 2 planes side by side I'll get no where because as soon as I collide with the other it will bring me back to camera one.     I apologise if I'm misunderstanding you.

@Ayush look at the blend file in the link

This is a state-full solution. Beside the event you measure what state you currently have. Usually you would check what camera is active. As this is not possible without Python you can use a proxy (the property). It is important to keep the property and the active camera in sync. This means when you switch to camera A, the property always switches to 1. When you switch to camera B the property always switches to 0. Ensure to disable [True Level Triggering] at the collision sensors. Otherwise the cameras will constantly toggle.

Go to the game logic editor and under actuator select scene then select set camera where it says restart. Then choose which which camera you want. Make sure to set the sensor for ever you need.


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Why does render to texture camera make armature animation freeze in the Game engine?
I needed to make an in-game, realtime mirror, so I set everyhting up as shown in this video, including the render-to-texture script. However, when my character is outside the range of the mirror's camera, all armature animations suddenly stop. I've set up a control (cube with simple armature inside), and all other animations seem to work fine, as well as movements. Only the armature animations are frozen when not within the range of the mirror's camera. Please help! Here is the .blend file.

There is a "animation culling" build in. This means anything that is not seen by the active camera will not be animated. This is to skip processing time.
This is not always a correct assumption, e.g. when the animation influences physics or as in your case you see it by a different camera.
I know this issue was raised as a bug to allow disabling this sort of culling for certain objects. Just now I do not know the state of that feature.

Damn. Thanks though. All I managed to do to get around it is to use a Near sensor (instead of the usual Always) to trigger the script controller, which isn't the cleanest fix but oh well.


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Fluid is floating instead of falling?

Instead of falling into this sink that I made, the fluid floats above. I'm not quite sure what's causing this. As you can see, my Domain is large enough so that it shouldn't be a problem:

Settings:

My current .blend file can be found here.

Try re-baking your fluid

The main reason for that behaviour are non-manifold mesh and unapplied transforms.

Non-manifold mesh used as obstacle.
One of the common options for different fluid objects is Volume Initialization. Only one value, which is Shell, can work regardless whether mesh is opened, i.e. non-manifold, or not. Two others assume that mesh is closed and thus won't initialize volume of obstacle (in this case) as expected.
In your file the sink object, where water is supposed to fall down after flooding the top box, is a plane with a Solidify modifier for adding thickness:

Non-manifold geometry is shown as selected
The object is set up to use Volume Initialization > Both which requires manifold object (you can change it to Shell though and simulation will work).
The mentioned modifier, supposed to make the object as manifold, won't be taken into account as it is placed below Fluid one in the stack of modifiers. However you can't move it above Fluid modifier because the latter requires original data of the object to work. Thus you end up either with applying Solidify or extruding faces in Edit mode.
Unapplied transforms on objects used in simulation
In order modifier to work as expected, transforms (scale, rotating) should be applied to object data. See more in Why is it important to apply transformation to an objects data?.
They aren't applied for all objects used in simulation. It is important at least for object with Solidify modifier for correct adding thickness to the mesh (and I recommend making its faces planar, e.g. with Mesh > Clean-up > Make Planar Faces). Note that leaving other transforms unapplied may lead to unexpected results too (although fluid simulation will work).
With that done, fluid will act as expected:


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Boolean through prison holes
I am trying to make a boolean on a wall in order for it to pass through the prison door without it showing up, but then continue onto the next door.
Any tips?

I am not sure what you want and what is your problem. Do you want to union, difference it from the wall? Do you want to make a hole in the shape of those door in the wall? Also if you want to repeat, just duplicate this gate

I want the use the boolean on the wall so that when it reaches the prison door, it doesnt pass throught it. Basically i want the wall to make holes on the prison door.

For the non-destructive option:
Forget about using the gate and make a new solid shape with no Render Visibility for the Boolean Modifier.

It should be as simple as possible while following the general shape of the cut you need.  It may be necessary to use a Subdivision Surface set to Simple on the wall to give it more geometry so the boolean doesn't result in artifacts.

This is actually not meant to be seen this close up so I haven't worried about the internals here, but you get the idea.
Also worth noting that the Boolean Modifier has two Solver options.  If one fails, see if the other works better for you.

It worked! Thank you!

@HelpWithPrisonProject glad I could help


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How to I create edge loops on an Irregularly shaped Blocks in Blender?
I used the Blender GIS Add-on to import some buildings. I now need to refine some of the buildings and in this case remove a rectangular block from the centre of this block.
I initially tried to use Edge loops on the top face to create a rectangle I could inset in the centre but because the top face isn't regular I don't think I can use edge loops? I've seen posts on remeshing but that didn't seem to work. Could someone point me at a tutorial or suggest how to work with irregularly shaped blocks like this?

Search for Knife projection ... Or only Knife operator to Cut through ... Or Boolean?

Select the top face, press Shift 7 to get the object perpendicular to the view:

Activate the knife with K, press Z to cut through, press C to cut perpendicularly to the view:

Create as many edge loops as necessary:

Select the faces on top and bottom:

Press CtrlE > Bridge Edge Loops:

There are various ways you can make an object intersect into another object or add edge loops, some examples are the bool tool, boolean modifier, the knife project or the knife tool. I commonly use the bool tool because I personally think that it`s way easier than the rest, but if you want to create edge loops then I strongly recommend you to use the knife tool. The bool tool and the Boolean modifier are similar to each other. The difference is that the bool tool is an add-on and the Boolean is a modifier.
1. Bool Tool

Just go to edit> prefernces> addons, search 'Bool tool' and enable the free built-in addon.

Now first select ' the object that you want to be cut on another object ' and then select the second ' object in which you want another object to be cut on' [tried my best to make simple as I could :) ]. Then press 'N', go to the edit tab and open up the 'Bool tool' dropdown and then finally press 'Difference'.
2. Boolean modifier

First, select the object in which you want another object to be cut on, go to the modifiers tab, select the boolean modifier, in the boolean setting select your object by either typing its name or selecting it with the eyedropper in the 'object'
NOTE: If you want the cut to be permanent on the object just select the Boolean modifier and press 'Ctrl + A' to apply it. (steps aren't included in the GIF)
3.Knife tool

Select your object, tab into edit mode, press 'K' to enable Knife tool, then draw your shape and if you want press 'C' to make a perfect horizontal or vertical line and then press the 'enter' key when you are finished.

Regarding permanent booleans (with the Bool Tool installed), you can alternatively use CTRL+Shift+B to bring up the Bool Tool floating panel. The top 'Auto Boolean' operations are destructive versions that don't leave any live boolean modifiers, while the bottom 'Brush Boolean' set does.


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Point > Align Rotation to Vector Node is missing in 3.0 and 3.1
I'm trying to follow along this tutorial by Erindale on youtube
I am using blender 3.0 as he suggests in the beginning of the video. Same as he is using.
I reach a point in the video (10:04) where he creates a "Align Rotation to Vector" node. This is selected as a sub-menu option in the "Point" Menu. For some reason, this does not exist in the version I am using, but it does in his?
I searched all the options in the top search bar, and the node is gone.
I tried blender 2.97, and boom the Point menu, and sub-menu are there, with the missing node. But other nodes required for the project are missing.
Has this node been removed/renamed since this tutorial was created in June 2021?
Do I need to downgrade to a different (non-beta) version?

I've also tried 3.1 Alpha, still nothing.

It's called Align Euler to Vector I think now.

Since they completely overhauled geometry nodes for 3.0, there's so much tutorial content out there (based on 2.9) that doesn't work anymore. You might be able to adapt what you're doing there to something like this? https://i.sstatic.net/X3mnV.png

To give some context to Ewo's answer:
In the video, Erindale is using an early Version of Blender 3.0 alpha.
This attribute-driven approach of Geometry Nodes has since been overhauled and replaced with what's called 'fields'.
That is why none of the nodes in the release version of 3.0 (or any build of 3.1 for that matter) look like they did in the tutorial. It's a completely different system now.
If you still want to follow the tutorial closely, you can reactivate the old system. (As described in Ewo's answer.) Keep in mind that you'll only see the "Experimental" tab if you have "Developers Extras" enabled under "Interface"

You have to enable Geometry Nodes Legacy under the settings:
Edit > Preferences > Experimental > Geometry Nodes Legacy
(and don't forget to Save Preferences)

You have to use Align Euler to Vector with either Transform or Vector Rotate + Set Position on 3.0+ to perform that operation.
I don't have the time or patience to watch the tutorial to figure out if you're modifying real geometry or instances, but if it's instances you'll also need to Realize Instances before altering their rotation.


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What is the best option for exporting complex step to mesh?
I designed a complex model in Freecad and now I want to add textures and render it for a product page.
This has ~350 solids. It's a machine which has subassemblies.
This is what I tried:

Exporting as STEP file and importing in Fusion360 and add textures there
PROS: Works great and fusion has a good amount of materials
CONS: The textures I want to apply are custom (i.e image/maps) and fusion doesn't support that.

2.1) In Freecad - export the whole file as OBJ as is and import in blender

Here the export contains a single element that only accepts one texture

2.2) In Freecad - convert solids to mesh and export meshes as obj

The good part is that this works and keeps the objects separate
The bad part is that I have 350+ solids and this is tedious.

What would you do?
Here rendering in Fusion to grab your attention

"Here the export contains a single element that only accepts one texture" https://blender.stackexchange.com/questions/516/add-different-materials-to-different-parts-of-a-mesh

Unfortunately adding texture to individual parts of a single mesh is not feasible here. The model has literally millions of  triangles.

@bem22 I'm sorry I have to tell you although you might find the methods "tedious" or "not feasible", there is no magic spell to properly transfer highly complex models between different softwares without any compromises or manually improving the result. And even if the model has millions of triangles, you don't have to select each single triangle - there are ways like box select, circle select, select linked etc. to select larger amounts or areas of a mesh that should share the same material.

@GordonBrinkmann Thank you for your input. I found a solution for my problem and I'm going to create a write-up.

I spent some time working on this issue and here is an answer that is fully open source. Yes, you can create great renders of your models freely, with some effort.
This solution is focused on improving solid model to beautiful render workflow
TLDR; and jump to 3) Solution if you are not interested in the synthesis
1. Create/Import your model
You are likely reading this because you either created a model in a CAD software or you have found STEP files for a model you would like to shade and render.
In my case, I designed the model using Freecad 0.19.2 and I also merged some models that were already available.
2. Problems with .obj + .mtl export
If you try to export your multi-component model as an .obj file and then import it to blender, you will face one of the following issues:
a) Blender will see a single unshaded mesh object and texturing this is imposible, considering that the model has 350 parts

The example above is a singular mesh with no shading and is rendered with using Cycles render and standard lighting

b) You export your model as obj + mtl and every component is shaded. However, when you import this to Blender, Blender will assign all of your materials to a single mesh, respecting the position of the materials on the individual parts (parts of the single mesh)

The black plate and the coloured components in the green highlight are all part of the same mesh. The element in the red rectangle shows this. You can also see that there are 26 materials applied on this mesh. Adding customization to this is close to impossible for more components because it's hard to which one you are editing.

c) You can also export all objects individually and then "assemble" them in Blender, which even sounds hard - however, with this you lose the hierarchy you have in the CAD software and management and workflow, again, broken
3. Export your models using glTF
Read more about glTF here
This file format is going to achieve the following:

The solid/body to mesh conversion from the exporting software is automatic based on global settings that you can play with (for max number of vertices/triangles etc)
Keep meshes separate
Retain your object hierarchy from CAD
Retain your material properties, for each object in the hierarchy

Unfortunately Freecad 0.19.2 doesn't offer this out of the box, BUT I found out that Freecad 0.20 is being prepared and there are weekly builds.
My solution was to use Freecad 0.20 (mid-November release) which supports exports to glTF 2.
To do this, select your model and go to File -> Export and select glTF.
Here's what my hierarchy looks like in Freecad

And here's the model after shading in Blender.

I altered the hierarchy in Blender a bit to improve my workflow

Although I don't understand the algorithm behind the glTF 2 export from Freecad, I can tell that for my model which is fairly complex, the process is almost instant (unlike exporting to obj or first creating meshes and then exporting)


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Blender import - What's the difference between Wavefront and Alias Mesh?
I'm building a project that has a PCB (printed circuit board).
I designed this using EasyEDA - Link to the project
I exported the 3D model from it. This creates an .obj and a  .mtl file in an archive.
When I'm importing this file in blender (File -> Import -> Wavefront .obj) an object is created in the collection, but only a dot appears in the 3D viewport.

I looked at the scaling of the object (doesn't appear to be neither too small or too large).
After I was hopeless with Blender, I decided to try in Freecad.
In Freecad there seem to be two options for importing .obj files: Wavefront .obj and Alias Mesh. When I tried importing the .obj using Wavefront, nothing was loaded (practically no model appeared, no error was thrown). However, when I tried with Alias Mesh, the model suddenly loaded successfully.
To confirm it was not a fluke I repeated this and then I went on sketchfab.com and 3dviewer.net. Both sites displayed my model correctly with the textures too.

So I'm wondering what the difference is between the two standards (?) ? More importantly, why can't blender see it? Or what am I missing?
Note, I saw this answer Why does my object file show up as a dot? and it doesn't seem to be the same problem, but correct me if I'm wrong. As I said, I tried to rescale the object.
Note, if you want to generate the file and look at it, check the project link above, then go File -> Export -> 3D obj

According to this page there is no difference in the format.  However, OBJ does not have a world scale concept, and I suspect the only difference you're seeing is an apparent scale difference.

"I looked at the scaling of the object (doesn't appear to be neither too small or too large)." Your Dimensions panel says otherwise

@DuarteFarrajotaRamos what I mean is that I played with the values and I scaled it down. Compared to the other post I have 1/100 of the value. I have some meters whereas the other post has 5km

The project you linked in the question doesn't look like what you have in your pictures. I downloaded a project I did in EasyEDA and see: The scale is 1 unit = 0.0001 meters ( 0.1 mm), small holes don't seem to have been exported, components are colored but there are no textures, the origin is way off. Can you share your downloaded obj files?

Ron. Post an answer with the scale. I did not know how to see the scale you presented in your comment. I changed from the amove meter values to mm for all 3 dimensions and it scaled down. My object was indeed to large.

@RonJensen please post an answer so I can close the question

@bem22 I'll write up an answer later today, thanks

I downloaded a project I did in EasyEDA and saw: The scale is 1 unit = 1 mil (0.01 inches or 0.254 mm), small holes don't seem to have been exported, components are colored but there are no textures.

Import the obj file using default settings
Make sure the new object is active and click Object->Origin to Geometry
Open the Transform panel n and set Scale to 0.000254,  Location to 0.0, and Rotation to 0.0
Adjust units to taste on the Scene Properties panel

I added the traces by exporting PNGs from EasyEDA and UV mapping the board mesh.


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Fluid going through a surface even though it is an obstacle
I have a problem with fluid going through an object even though I set it to be an Obstacle. I made a video explaining my problem.
Settings:

.blend and other related files here.

Aside: in case you don't know, you can Ctrl-click or double-click on an object's name to rename it within Blender, so that you can see your handy labels while you work!

For your Obstacle object, under Properties panel> Physics > Fluid > Volume Initialization:, select Shell.

Another thing that sometimes helps is adding a "solidify" modifier to your object. This gives the object a thickness that can help with fluid aberrations. This modifier must be applied or at least above the other modifiers in the stack to work properly.

I had the same issue (object not interacting at all with the fluid, whereas primitives like a cube would interact correctly)
Turns out in my case Export Animated Mesh had to be checked on the obstacle object


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Rounding Evenly the Edges of a Scaled Cube
I have a question about rounding the edges (of a cube). For example, I have a simple cube. What I don't get is how do I round the edges (like on an iPhone):

I tried to do something like this, but Picture 2 was the result.
How do I round the ends of my cube like in Picture 3?

A quick way to add rounded corners is to use the Bevel modifier to your cube or starting mesh:

Use the Width, Segments and Profile settings to control the shape of the curved corner or edges. Profile controls shape of the bevel, from concave to convex, but has no effect if your "Segments" settings is less than 2.
You can add a subsurf modifier, as well, to add additional smoothness:

Both of these modifiers  can be applied to your mesh by clicking the "Apply" button... this makes the changes a permanent part of your geometry. Or you can continue to use and render the items within Blnder with the modifiers in place and unapplied.
These are very basic ways to do bevels and rounded corners. Blender has a number of tools to give you control of specific aspects of the Bevel and to limit it to specific parts of the mesh. See here for examples:
Bevel specific edges

this helps, but when I trying to scale cube to x/y/z axis that ellipse, not round :(

Key Ctrl + A and select Scale. This makes it so that the scaling of your cube does not stretch the bevel.

Take a plane and size in rectangular shape
Go to top view (Numpad 7)
Go to edit mode
Select the all the vertex
Press shift+clt+B and drag and make the arc and scroll to increase the segments
Go to side view (Numpad 3)
Extrude the vertex
Apply smooth Shading
Add Edge split modifier


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Frame rate drops in video editor

Hey everyone! So im a little confused here and im extremely new to the world of video editing. My brain is hurting but it feels really rewarding. Anyways, my first problem that I am having is in video editing mode (obviously) with the video playback. I believe it is called video sequence editor. For the first three or so seconds, it runs at 55 - 60 fps (even though the video is at 30) and then it almost starts playing in slow motion at 2.50 - 5 fps!! What the real kicker for me is, the video is at 30 frames per second, but it actually looks fully up to speed when it reads 60 fps. Anything below that, it plays almost in slow motion. Actually, very slowly.
I have manually set the fps to 30, tried again without manually setting it and still no luck.
Thanks all!

Whenever it's red/drops below actual frame rate means it hasn't "cached" those frames. Because Blender works in frames of a video, not time, it needs to cache, or store, each frame. When it drops below the frame rate its saying "These are all new frames to me" and it runs slower. So play it through a couple times, and it will cache the frames. Also you can change the number of cached frames in the settings. I'll turn this into a proper answer later I just don't have the time now.

My experience when this happens is that it doesn't affect the final output video's speed.

http://getgreenshot.org/de/ - it's a great tool to make Screenshots. You can upload them directly to imgur to use them in your posts...

Why Is It Slow?
1. The V.S.E. , unlike your typical video editor, is frame dependent. Most others rely on time. This is why you must set the correct fps in the properties panel. Which you did, great!
Second Blender has to "cache" those frames. So when you play it through it takes each frame and saves a temporary version of it. But, the farther you go the more it will struggle to cache it, meaning you may have to play through it a couple times for it to work.
OR
2. You've reached the maximum cache...
Ok... So how do I fix that?
To change max cache press CTRL+ALT+U to bring up user preferences. Head over to the last tab labeled System and scroll down to the bottom where you'll see Sequencer/Clip:Editor. Go ahead and set that to your RAM. You can go even higher if you want; I can't guarantee what will happen. Make sure to save your user settings.

Other Things You Can Try:
1. Use that handy-dandy proxy setting. Right click on your video, and set that proxy! Then you'll have to go down and press Rebuild Proxy and Timecode Indices
Use frame dropping or Av-sync. Use it, it does what it says. Drops frames to run faster.
Last Thing
Not entirely sure why it says it runs at 60 fps (its not), but I suppose its just saying hey, this is how fast I can run.
Also know that this will NOT affect the final render in any way, only in the viewport.


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How to move along depth axis on a mac?
If I want to move the user view in Mac, I can do it by pressing Alt + Shift + LeftMouseButton. Note that I just have a trackpad, not a mouse. Anyway, the problem is that this way I can just move along two axes. To make this clear I took a video, which you can see here.
Like you see in the video I can only move just along the Y and Z axes, not along the X axis. If I wanted to move the user view in order to look at the back of the cube. I had first to rotate the camera and then move the visual again, which is doable but it's not fast/comfortable at all. I need a way (possibly a shortcut) to move the user view along the X axis.

You track forward/backward the same way that you scroll a web page. Often, a trackpad does this this with a two-finger drag up and down.
Note, that even when this works correctly, it will still not allow you to view the back side of the cube. By default, it will track toward an invisible pivot point i the center of the view. As it approaches that point, the track will become slower and slower, so that you never go past that point.
If you want to view the opposite side of you cube, you will have to rotate. But there is a setting that makes this a little easier. In User Preferences in the Interface tab, turn on "Rotate Around Selection."

This will force the view to orbit whatever object you have selected, instead of orbiting the center of the view. This will make it MUCH easier to just rotate around to the other side of an object. Check out the other options there, as many of them are very useful.

For this answer to work, you will need to enable something in the User Preferences. Go to File > User Preferences... > Input and check Emulate Numpad at the middle left, if it isn't already. From here, you can key 1, 3, or 7 to rotate the view around. From one of these rotated views, you can surely do what you've been doing, except this time along the X-axis.
Note that Ctrl + 1, 3, or 7 will rotate 180 degrees opposite plain 1, 3, or 7.

So the only way is to rotate around my object? isn't there a way to directly move towards the object?

With a mouse, you could scroll. I don't think there is a way with just a trackpad. Also, if my answer helped, please consider accepting it.


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Why do some parts of my object disappear when viewing the render viewport from certain angles?
So I dont know a whole lot about blender, just the basics. I am trying to build a 3d model of a room in my house. Following a tutorial online to make the wood look more photo realistic, I added a PBR shader to the object. The floor becomes all distorted when viewing it from certain angles. The guy that did the tutorial had his looking nice and I thought I followed it precisely, but I can't figure out why this is happening. See the screenshots for a better explanation.

i don't think it "disappears" as such, but starts reflecting the background world colour, like a mirror

it's a bit too glossy and probably not enough normal map effect, but we can't see what's happening within the node group, so maybe pack the images and share your file

I would start with a Principled BSDF shader, but since you are following a tutorial, try increasing the roughness to see if that helps minimize how much of the environment is being reflected.


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BGE my animation won't play
I started using blender some time ago and used the wiki book on blender to learn how to use it. So I want to test out putting an animation action in the game engine and I've downloaded a low poly human mesh, removed the vertex groups and made my own armature and made a simple walk animation. I did add the subdivision surface modifier but whether I place the armature modifier above the subdivision surface modifier or apply it the animation won't play. The game logic is sound I've added an action actuator in addition to a character motion actuator and I use the W key for movement to test if the animation would work. I've made the human mesh the character physics type and activated actor. Where am I going wrong?

Please rephrase the title to a specific question to find helping people easier. Form the information you provide I can't tell what the problem is. Some screenshots might be good (logic, modifiers etc.).

Just now I do not see a misconfiguration (the Character Physics type and the motion actuator are irrelevant here). You wrote you removed the vertex groups. Did you get the vertex groups back by parenting via Armature Deform with ... weights?

Not the same ones that were in the original file but I did with a few additional ones too

I guess I would need to see a blend file.

Here's the link there are 3 files but the one with the ending .blend1 is the correct one.  https://drive.google.com/folderview?id=0B3y6_KANitapWHlSRy1fRXJmeWM


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Normals issue when applying "solidify" modifier
This doll´s hand´s mesh seems to be ok until I apply "solidfy".
I did mesh>normals>recalculate outside & recalculate inside
I applied EdgeSplit modifier (as they suggested in other answers)
Nothing happens.
In geometry>face orientation nothing is shown also
Any idea?
(thanks a lot)
Hi you all.
I made what you asked and suddenly it seems not to distort so heavily. Anyway, it still distorts.
The only diference between picture 1 and 2: solidify applied with Rim> fill, Offset> 1.0000, and Thickness> 0.002m

It seems to have something to do with the mesh, despite it is quite simple. The distortion evolves from the simple mesh to the chaos in some points, as in the slot and one of the two holes I made in the sides ... Any idea for cleaning that mesh up?

The mesh blows up like this once you apply the modifier ? can you show it without modifier ?

hello could you please share your file with the modifier unapplied? https://blend-exchange.com/

hard to say without the file, also, why do you need thickness?

Because I wan to print this


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I have a problem when i try to bulid blender manual on linux
I am trying to build Blender manual on my Linux system but I have this problem:

Can you help me?
Thanks in advance.

A guess: you have an old version of sphinx-build that doesn't support the auto argument to -f. Read this sphinx-build reference. As an experiment you could try something like this at the command line,
$ SPHINXOPTS="-j 2 -D language=en" make html

which will override the default -j parameter (the number of parallel processes).


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First time rigging. What am I doing wrong?
I'm new to Blender. I managed to create a pretty good 3D version of a mascot. I want to rig the mascot but it's a weird shape and I'm not sure how to get this to work. I've used symmetrize and IK Constraints. When I parent with automatic weights, I have to correct a lot of it with weight painting as it's deforming the shape of the character too much but that gets too messy to sort out. Any tips would be appreciated.

I would start making the "shoulder" bones child of the head bone, and top arm bones child of the torso bone, so that 2/3 of the big sphere moves as one piece. Then with such a particular shape some manual weight paint is needed indeed.

Thanks! I will try this

Well The sphere seems better but the legs are contorted and I can't undo it with weight painting. Starting to think I need to put my character in a more traditional t-pose in order to get the rig to work.

If you need some more help, please provide the file, or some pictures of the problems and the wireframe of the character.

https://drive.google.com/file/d/1VGCFG9Zo5Kz0u0yAaDfipl8aCDy22D-p/view?usp=sharing

Basically once I parent with automatic weights, the arms, legs and butt/hip region are warped and when I try correcting it with weight painting it gets messy. The file I provided above is not yet parented.

340 Mb is too much. I think you need a retopology before attempting at rigging.

Ok thanks I will give that a try. I really appreciate the advice.

Is it possible to use decimate, boolean and/or remesh modiefiers to make it more simple rather than manual retopology?

Update- I got the file size down to about 10,000 kb by simplifying the mesh and reducing the number of faces and vertices. How I did that was by changing the subdivisions I added to smooth the surfaces to the lowest number possible, I also used decimate with Collapse mode to lower the Ratio number as far as I could. I also went in and deleted some extra vertices that were hidden inside the character's body. After getting everything as low-poly as possible without ruining its curvature, I then reconstructed the rig from scratch and Parented the rig to the character with automatic weights.


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Can I use the python API to convert object intersection coordinates to UV coordinates?
Let's say I have a cube with a texture on it, and in edit mode I place the mouse cursor over some part of the cube. Is it possible to get the location of where the cursor is pointing (intersection test with cursor ray) and convert these coordinates to UV coordinates? And to also go the other way, given UV coordinate, find the object space coordinates? Can this be done with the Python API?

The UV -> object space is more tricky, because the UV may point to several object space locations, or nowhere.

@zerocukor287 That's fine, it can be filtered after based on some criteria.

The first thing I think of is actual texture painting, so I might look into reusing that.


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Instance action with Animation Nodes
I wish to create randomize action for a walking crowd and even more to learn how to do it with Animation Nodes .
I have some issues to clarify but to start with I cannot instance the character properly.
to make the long story short my question is how to instance with animation nodes a character that is rigged.
As for long story - here's the details of what I did and the attached file:
blend file
a. I could create it with particles (See the blend file Particles collection) - which is less interesting as AN enables many options that I cannot do with particles - randomize the action, collisions etc'.
b. I tried two AN trees, both didn't worked properly.

The Instance tree (the number is set to zero so it won't interfere the other AN tree).
did add the meshes but deformed. As if they instances have some issue with weight paint or Scaling.

The Action tree - gave more or less the same result... {and seems to me a better path to explore as I'd with after to randomize the action, but assigning different actions (from a given pool) to the instances}.

I tried it with different actions, on rigify and mixamo actions... different meshes, armatures. The results were more or less the same. It seems thatthe further the vertices are from the center the more they are distorted.

you should use https://blend-exchange.giantcowfilms.com/ to show us your blend file - nobody wants to ask for permission just to download your file....and the second reason: if you delete your file, nobody can check it again....

Thanks, I wasn't aware of it. I uploaded and edited the post also here -

Foreword
Yes, I'm aware that this question is 9 months old, and I assume that the OP has either figured out the problem or moved on, but since I was having the exact same problem and I was finally able to come up with a solution (through a lot of struggle) , I'm going to post an answer for future reference. I had better luck understanding the problem with the provided .blend file than my own, so I'm grateful to the OP for providing it.
Note, I am also a beginner with animation nodes and blender animation in general, so keep that in mind.  I have provided an updated .blend file, a modification of the original here:
In particular, reference scene "node_tree_vt_4" for my final solution.  I'll also provide some screen shots.
Analysis
This problem really has nothing to do with animation nodes: it's a problem that you would still have if you were manually trying to duplicate a full mesh-rig improperly as well. Although it's not technically an AN problem, I did implement the solution with animation nodes, and indeed you're more likely to experience it when duplicating with AN.
Basically, the problem being made is you're only instancing the mesh, not the rig as well.  Normally, when you manually copy a rigged object, you box select the object or select "select hierarchy" from the scene collection, so you naturally select the mesh and the rig so you don't have this problem.  However, when you use AN node "Object Instancer" on the target object, it will only duplicate the mesh.  And that object, will have an armature associated via a modifier (this was a key thing for me to understand).  Here is an example of the armature for the clive base object:

Note that when you instance the base clive object with AN, it will create "clive.001", "clive.002" etc., but if you look at their linked armature you'll see they're still referencing 'clive.rig' which is still located at 0, 0, 0 and that's why they're skewed: they're attached to an armature at the origin, not where they are located.
To fix the problem you have to instantiate and move the base rig as well.
So here's a couple of screen shots. Note how in the following "clive.002" is properly associated with "clive.rig.002" and how none of the objects are skewed.  In the following "1" is where we created the meshes, "2" is where we create the armatures/rigs, "3" is where we loop over the meshes and rigs and assign the proper rig to the mesh, and "4" is where we do the animation:

Here is a closeup of the new part of the AN in case the first is hard to see:

Final Thoughts
Performance appears to be a potential problem.  With 4 armatures I'm getting about 1.6 ms per animation frame, and with 10 armatures I'm up to 10 ms.  To get 30 fps you're updates have to be less than about 30 ms.  Typical AN updates times are on the order of .07 seconds, so it's takes quite a bit of overhead to do it using AN.  This might be where I don't know enough about AN: in one of my attempts I was getting 340ms until I re-implemented it in "node_tree_vt_4" and got it down to 1.6 ms.  You may want to separate out the creation of the meshes and rigs from the animation step anyway, because you essentially only have to run the "create" step if you change your "n".  However, even then, I'm not sure if you'll be able to get real-time animation if n=1000, for instance -- although you should still be able to bake it.
Also keep in mind that mixamo armatures can have their own coordinate system e.g. x and y are interchanged, and distances are in centimeters not meters, so on my own project if I want to move the armature 2m on x-axis, I actually have to move it 200 on the y-axis.

Thanks so much for the detailed explenation. It is a good remainder not to take for granted that the scene object are copied to AN. Well noted your observation per the calculation time, I'll inform if I come around a solution to move things faster.


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Difference: Caching and Baking
I've been playing with smoke and fluid simulators lately and I noticed that sometimes you can cache simulations while playing (Alt + A) the animation (but it only works at a very low fps) and sometimes you can't.
What is the expected behavior of this feature? I found it really useful for tuning properties, but sometimes the only way to see the simulation is by using the bake button instead of playing.

Caching is done with any type of physics (except for fluid simulation) while playing animation (files are being written to disk while animation is played) and everything will be cleared once any changes of settings are made. Note that you'll be able to edit settings of physics simulations on the fly, and previous cache will be cleared once animation playback started again (new values will be initialized).  It will not start if animation playback was started after starting frame of simulation.
Because of amount of computations done in real time, caching will last longer and speed of animation might be quite slow.

Caching

As animation is played, each physics system writes each frame to disk, between the simulation start and end frames. These files are stored in folders with prefix blendcache, next to the blend-file. Note that for the cache to fill up, one has to start playback before or on the frame that the simulation starts.
The cache is cleared automatically on changes - but not on all changes, so it may be necessary to free it manually e.g. if you change a force field.
Cache and Bake

Baking will pre-calculate animation taking into account every option set up and animation will not be changed unless bake freed or deleted. Once simulation is baked it is impossible to change most settings of objects used; meshes changes won't be taken into account and old results will be played instead.
However, no computations will be done in real time and animation playback will be faster.

Baking

The system is protected against changes after baking.
If the mesh is changed the simulation is not calculated anew.
Cache and Bake

Note also that baking physics simulations can be different in options depending on type of simulation, so several settings will depend on what you bake.

thank you for the in-depth answer.
I believe that was exactly the problem: starting after the first frame of simulation and maybe making changes that won't trigger the refresh.

Baking calculates every single frame, just like when rendering an animation. Caching is that it remembers the data so it can replay it. This means that caching is better for doing edits.

ok, so I may have misunderstood both concepts. But still, I can't figure why sometimes it simulates when I hit alt+a and sometimes it doesn't..


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Is it possible to pack a sequence of images into a .blend file?
I want to pack an animated texture (a sequence of images) into a .blend file, but for some reason, I can't do that. Is it possible?

Related: How do I completely remove an image from my .blend file?

You can of course pack many image data blocks,
but you can't pack the frames of an image where the Source is set to Image Sequence.


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How does one use cycle's image sequence?
I would like to create an animation where the source image changes at certain points. Cycles' Image Sequence setting on the Image Texture node looks hopeful. However, I can't seem to figure out what kind of input it wants.
Is this one of those images that are literally just a sequence of different images loaded on one? Thanks for any help!

You can use a sequence of numbered images as the input to an Image Texture node set to Image Sequence.
The key is to ensure your image filenames include a numeric element to represent the frame as the last part of the filename before the file extension - eg, 'flame_heat_fuel_000002.exr'.

Blender will identify the 'frame' part of the filename (in this case '000002') and use that to determine which image to pickup for the current animation frame, with the Frames, Start Frame, Offset manipulate how the Blender current frame maps to one of the image sequence frames :

'Frames' defines how many frames are in the sequence
'Start Frame' defines which timeline frame maps to the first image in the sequence
'Offset' shifts the animation along the image sequence by the specified number of frames (so an Offset of zero will map 1 to 1, 2 to 2, etc., while an offset of, say, 5 will map 1 to 6, 2 to 7, etc.)

Enable 'Cyclic' so as to loop the animation over the specified number of frames.
The Image Texture node shows the actual in-use frame just above the 'Frames' field. As you move along the timeline this will update to show which of the image frames is currently selected.

You can compile your images into a movie clip in the VSE. Note that each frame an image is present in your VSE video will be the number of frames it is shown by the Image Texture node (exceptish Offset:).
You can load a movie file into the Image Texture node. It will give you these settings:

Start Frame: should always be 1. Frames: should be the exact number of frames in your movie. Offset: is counted in frames and employed to start a clip later then the first frame.
You could also opt to load in multiple images and toggle them by keyframing a Mix Shader's Fac: value as shown in my answer here.


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How can i use an image as a background in Blender Render?
I mean to say that for reflective materials like metal, I want that image as world material so that I get the cool reflections.

Welcome to Blender.SE Milin. Please take a look around before asking in the future. A good amount of questions have been answered already. You can also see these as they might relate to what you want.. How to capture lighting in video shots? and How to make a model cast shadows onto the world texture/background?

Also, try to keep your posts as specific as possible, using OR wouldn't be ideal in this case as posts should ideally have one question and one answer, ask for both or one.


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Dissolve Edges in Text Object
I have a Text Object that I converted to a mesh:

I would like to reduce all the unnecessary edges like in the picture below (including the two I could not get rid of):

But instead of step by step dissolving edges (and then end up with some undissovable ones), I would like to achieve this in a simpler way.
Select the complete Text mesh (not just one letter) and dissolve all edges.
Unfortunately this does not work like that.
Also the Decimate object modifier just ends up distorting the Text/Font.
Is there an easy way to achieve this ?
Thanks

Ngons with holes are not supprted yet (2.77), so it's not strange that there be some edges that you won't be able to dissolve.

As Carlo said you can't have edge islands in the middle of ngons that are totally disconnected from the surrounding edges. Best you could do is 'minimize the damage' and manually choose where you place them so they look better. For example in the A I would place them at the bottom over the horizontal arm

I would leave it where you have more segments but they're all quads/tris. A more orderly mesh is better than a minimal one.


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how to replace vertex by another mesh?
I have (downloaded) a model, it is rigged, with weight, which (I guess) cause the mesh become some vertex group. can I replace part (or all) of the model vertex? with another mesh?

you can but the new mesh won't have the same vertex groups, unless you've created some vertex groups for this other mesh, that have the same names

so that mean I will lost all the rig, right? unless I rig it again.   I mean the vertex group is not manually grouped or named, it is (might be) automatic generated when rigged.

You can try the Data Transfer modifier with the previous object as Source, but if it doesn't work you need to parent With Automatic Weight