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Solidify a UV sphere that has a part transparent material?
Here is my problem:

I have a fluid simulation of a circular blob of water, and then a UV sphere encasing it. The UV sphere has a material that includes a diffuse and transparent node factored together by a Black and white image of the earth.
When I went to add a solidify modifier to make the 'land' touch the fluid but since the mesh is a UV sphere, not an actual sculpted piece of earth's terrain, the solidify modifier does not work. Any Ideas?
Image Texture Used: https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwi66Yiqso_KAhUI5iYKHd2aCVIQjRwIBw&url=http%3A%2F%2Fwww.blenderguru.com%2Ftutorials%2Fcreate-a-realistic-earth%2F&bvm=bv.110151844,d.eWE&psig=AFQjCNHObkXmNdYPEyyqGqGSLzfAi0-0hg&ust=1451970653008360

I found a solution:
First resize the UV sphere so it is a little bit smaller than the surface of the water and UV unwrap it. (Since I am using a distorted map of the earth that is meant for a sphere, sphere projecting the image will work perfectly.)
Second add a subdivision surface (more subdivides=better resolution) and a displacement map to the sphere. Lower the displacement strength down to .1 or .2 and Set the Texture Coordinates to UV:

Next add a new texture in the displacement modifier and edit the texture under the texture panel. Open the black and white image (Black=Transparent, white=terrain) of your choice and adjust the brightness to the desired amount. (Brightness changes how much terrain pops out.)

Finally, change the material to have a mix shader of diffuse and transparent, factored by the same black and white image used for the displacement:

Result (Not the best result but does work):


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What is the minimum size requirement for a Fluid mesh object in a Fluid simulation?
What is the minimum size requirement for a Fluid mesh object in a Fluid simulation? I've heard and read that if the mesh is too small, it may not act like fluid properly when baking. But, I don't know the exact measurements of "too small". Does anybody know?

I would imagine that has to do with the limitations of floating point numbers. they are intrinsically impossible to keep 100% accurate, so if you were to make the fluid work mainly within floating point operations, minor calculations would have a tendency to be off slightly and since simulations rely on previous calculations the slight error would compound into a greater problem. im not sure if that is the case but i know that in programming of all types, double precision decimals are recommended over floating point for that very reason

Is there a way to make my model & simulation not use floating point numbers?

without a doubt... but i wouldn't know how to do such a thing myself... that would involve editing the source code, that being said, the fact is that all things in the universe are relative to their perception... so if you scaled EVERYTHING up it should reduce the effects... again, i don't know that this is the case for a fact, but it makes sense since double naturally take twice the cpu and ram to work with, the devs would opt to use single precision float. i would have added an option to change this, and their may be one, but im still relatively new to blender. maybe post in the dev forum?

This is dependent on resolution.
Imagine the domain as a grid of 3D pixels (volumetric pixels, or voxels). If your fluid object is smaller than a voxel, then it can't be represented properly (even if it's two voxels, that's still not good)

To fix this, you can either increase the resolution (this will increase bake time), or scale down the domain (this shouldn't increase bake time, but obviously there is less room for the fluid).
Since the resolution defines a fixed number of voxels, scaling it down will give you the same number of voxels, but they will be smaller (making the fluid object relatively larger):

There may be a hard limit of how small you can go eventually, but anything remotely reasonable should be fine.

source: Stack Exchange

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

sort: votes


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Can loop cuts be snapped to anything other than increments?
I'm trying to make a loop cut slide along a face and snap to a vertex.
However, even though I have "snap to vertex" mode enabled, the loop cut slides on the face only in increments.
Am I doing something wrong, or is this a bug, or must I first place a loop cut, then G to grab it and drag it to snap to the vertex?

AFAIK, this is not possible atm, only transform operators (translate, rotate, scale) seem to use snapping settings. You'll notice that the loop cut and slide operator makes a loop cut, then runs the edge slide operator. The snapping you see when holding ctrl or shift+ctrl is only constraining the relative offset of the edge slide operator to nice round numbers. As you said, I think the only way atm is to snap with a transform operator..

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Is there a way to have default mesh objects come with premarked UV unwrapping seams?
I was thinking it might be useful to have default mesh object such as cubes, cylinders or other objects like the platonic solids etc from addons to default to come with premarked UV unwrapping seams when added to a scene. Is there a way to do this, perhaps with the startup file? Here is an example of what I was thinking about:

AFAIK these objects are generated based on instructions in the code (it doesn't use "template" objects or anything like that). The only things I can think of are: 1. editing the source code of blender (and any addons which add new primitives) to generate meshes with seams, or 2. Creating your own seamed primitives with CreaPrim. (I'm not sure if it keeps the seams, I haven't tested this)

AFAIK, this is supported in some softwares such as TrueSpace, but not yet implemented into Blender.

Is this what you're looking for?

This creates a UV layout for an object on creation and is a feature in 2.77. You can download RC2 from the institute now.


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How can I get section of my armature's bones to trail behind when moving?
I've got a dragon armature and I'd like to have all the bones of his tail just flow behind him as he flies, without me having to position all the bones by hand along his flight path. Is there an easy way to do this?

Related: http://blender.stackexchange.com/q/8772/599

You mean the chain straight following the dragons motion path or using softbody physics like gandalf3 suggests?


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UV unwrap or geometry issue (cylindrical object)
I have created a mason jar object, and I am primarily having issues unwrapping the lid part of the mesh:

When attempting to unwrap properly and avoid an overhead projection type mythology that requires placing the rings in a separate location in the UV space, I am not sure how to reconcile the result of the unwrap.
I want to avoid a lengthy manual process of manually moving around vertices in the UV space to achieve a good result.

Using the unwrap methodology above yields seams when brought into Substance Painter and having materials applied.
I am also trying to unwrap the entire object onto one UV image and even at 2k, the results seem fairly low resolution.  I have made sure transformations were applied to the object prior to unwrap, so the relative size of different parts of the UV shouldn't be the issue.

My goal is to have a fairly clean unwrap that allows for as few seams as possible and a maximize usage of the UV space in a 2k image.
Is there a better way to mark the seams?
Is my overall geometry unsound for efficient UV unwrapping and maximizing use of space?
Also, the interior faces may be important as I plan on applying alpha transparency to the materials applied to the lid and jar of the object.
I have attached the blend file if anybody was interested in taking a look and pointing me in the right direction.

I plan to use the model in the Unity environment.
Thanks!

When adding a .blend, don't provide just the url of the website, please provide the link given at the site. Thank you!

The lid probably only needs a single UV seam on its lower inside edge.

Then you can arrange the UV's something like in the screenshot below:

Your jar was almost 2 meters tall. Unless you have a special reason not to I would suggest that you always model to real world dimensions. In this casxe scaling it down to size ( s 0.1  giving a more realistic jar hight of 180mm) means you get 10 times the texel density on the finished model when using the same size texture.
(2K texture for such a model seems a bit excessive :) )
Also, you have way to many edge loops in the Wires. I would suggest removing as many as 4 out of 5 in the Low version.

Beautiful!  Thanks for the response.

What was your methodology for straightening the verticle edges of the jar in the UV?  Did you select each edge and scale to 0 or is there a faster method?  Thanks.

To straighten edges; For the first edge : Alt LMB to select edge, RMB to open the context menu popup and choose either the Align X or Align Y option. For the next edge : Alt LMB the the key board short cut to Repeat Last operation which is Shft R but I have my repeat last operation mapped to a single key (tilde key  ( ~ ) which I find quicker and easier to use.

Appreciate the help, thanks!

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


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Can a procedural texture follow the x y z orientation of vertices or do I need to UV unwrap?
So lets say:
I want to avoid seams on my model.
I'm to lazy to UV unwrap.
I want to keep my mesh joined.
Would it be possible to create a procedural material that follows the xyz orientation of a vertex or a vertex group?
The first screenshot is what I have and the 2nd one is what I want to achieve in terms of, the material following the xyz orientation. It has seams now which ruins the procedural aspect of it.
I found this but its not really what I want need, but goes in a similair direction.

I hope this is clear.
Hope I didn't violate any rules.
First post, thanks in advance,
Paul

Hello :). If you split the table into individual planks, then Object coordinates should give you such result.

You can also unwrap automatically, with UV > Smart UV project. Works really well for this type of geometry.

related https://blender.stackexchange.com/a/113922/19156

Hey thanks a lot for the answers. Yes, the second image is Smart UV projected, but I dont want to have seems. Splitting in individual planks indeed works, but thats what i wanted to avoid :)

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Problem rendering Fluid Simulation
I tried Blender for the first time yesterday. I wanted to mess with the fluid simulations and it worked.
I used a tutorial and everything turned out fine except when I wanted to render the result. The first time it worked but the problem was, that I forgot to select an output file, so I had to do it once again. This was the point, when it started acting up.
https://drive.google.com/file/d/1JcVVVyihO77TxkVDQHWbjw8sDS0fn0qS/view?usp=sharing
This is what I got.
Has anyone got any idea why is this happening ?

Adding to the previous answer, the fact that the domain wasn't baked is likely a factor.
You can re-bake the domain by going to the domain properties and selecting "Bake". (2.81 and before). If you are using an experimental build (2.82+), then mantaflow will be included. In the mantaflow domain settings, select "resume bake".
I personally would recommend that you create a bake directory if you haven't already, so that you can see where your bake files are all going + it isn't saved in a temp folder. Temp folder bakes (the preset) can cause issues like this every now and then, and you won't be able to access them if you want to open the .blend on another device, or if you bake another fluid simulation to the temp file again.
If you haven't done this already, then you can set the domain bake to the file browser icon in the fluid domain settings. Select this, then browse your computer for a file to bake to. This is best done in an empty file.

My best bet is that the fluid was not successfully baked. That's why it turned back into the domain mesh.
(I have noticed that it has been some time since you make this question and you may have already known this. But if not, hope it helps.)


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Render is all gray, tried multiple things
I'm trying to render an animation I made using blender models and textures, but all I get is a grey screen on the Rendered viewport and output.
On the left there's a Rendered Camera view, and on the right my objects in the Solid Viewport

I tried doing some researching to see what I was doing wrong, but unfortunately I couldn't find anything. Here's what I've tried:

See if something is up with lighting and camera, and apparently it's not;
Disabling "Sequencer" from Render > Post Processing;
Switch from Blender Render to Cycles Render, but it didn't worked either and the output it's the same;
Copy one of the objects from the original scene and place it on a new Blender file, containing just the starting cube. When I rendered through Blender Render, I could only see the cube. However, when rendering through Cycles, it rendered both objects with their following materials.

Here's the experiment on a new Blender file, and the Rendered view shows both objects

Do you guys have any suggestions of what my problem might be?
EDIT: addded .blend file below.

Please post your blend file so we can take a look at it.

Welcome to the site. It may expedite getting an answer if you upload your a copy of your ~.blend file to http://blend-exchange.giantcowfilms.com/ or a different hosting site of your choice, and edit your posted question to include a link to the file.

You're getting a grey screen, because all your objects are set to be visible but not render.
If you check the outliner, you'll see that your "Skybox" object, "Bola" object as well as the spheres parented to the armatures are all set to not render (the camera icon is greyed out).

For each item that should be rendering, click the camera icon beside each one in the outliner.


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'Child of' Constraint, setting Inverse doesn't work?
I want to parent a mag to the left Hand Thumb but once I target my Armature the mag absolutely changes LOCATION / ROTATION / SCALE this is really weird, I mean even setting it inverse doesn't help. I need assisstence. I tried doing this over a dozen times, but I just can't get it right.
My Blend file below:

Or maybe there is a better way to do it, easier without the Constraint ?
basicly what I want is to animate the parent of the Mag to the thumb bone.
Thats what I see once the Constraint is applied:

By uploading it the BE you a agree to the Terms of Service, which lets us distribute it however we wan't, including commercially. Please request removal if this is a problem.

The Mag is moving/rotating relative to the gun (since it's parented to the gun).
PLUS the Child Constraint adds it's Position/Rotation also to it. This causes the mess I guess.
How I fixed it:

Set influence of the Child of-Constraint to 0
Go to the last but one keyframe (99, where the mag is inside the gun correctly)
Delete all the keyframes for the mag
Now the mag should be inside the gun the whole time when the animation plays.
Keyframe the influence at frame 0 and the frame before pulling out the mag to 0. Also set keyframes for the mag /LocRot at the same key-positions.
Add another keyframe, where the hand will pull out the mag and set the influence of the constraint to 100. You will notice that the Mag is going to change it's position, now position it correctly for this keyframe.
Done, for the rest of the animation, the Mag is following the thumb.

Maybe you check out this "tutorial": https://www.youtube.com/watch?v=3Jx5X3fG4bY ... not professional, but seems to work (somewhere in the middle he has the same problem).
Here's the blend file:

Problem is, if you move the gun, while pulling out the mag, the mag itself will get an offset and will "drift" away...
Hope this helped a bit

The problem is double parent transformations:

first from parent
second from child_of_constraint

The solution and how to cleanly set this up is:

do not give the Mag any parent, all parenting will be done with constraints
position the Mag so it is both in the gun and in the hand
set 1st child_of_constraint to the gun and Set inverse
set 2nd child_of_constraint to the thumb and Set inverse
switch parenting with key-framing both constraint influences, gun_parent will go from 1 to 0 and hand_parent vice-versa.


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Morph between vertex color from instancer
I have some trouble to morph between two vertex color.
I made a morphing between two point cloud without problem, but when I try to morph vertex color, the first one is ok but second one stay black (and if change 1st and 2nd, 2nd is ok and first is black ..)

If someone knows about it I will be grateful !
Best regards

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.

could you provide an example file over https://blend-exchange.com/?

In the first image you can see the GN morphing between them.
Second is my material for my point cloud (it's a ply file import and draw with instance of point)
The last one is the morphing between the two material with attribute
If I morph my first point cloud to the second, it's ok but o for the material, I can have the first material but second one is still black, I think it's maybe a problem of vertex color attribute !?

Why Attribute uses Instancer mode? I don't see any instancing in your setup

I put instancer because I draw the point cloud with instance of triangle, if I put object or geometry nothing happend !
(I edit my post with GN for the point cloud!)

For info I imported PLY files as VERTS/COLORS ONLY with this :
https://github.com/TombstoneTumbleweedArt/import-ply-as-verts


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Geometry Nodes - Get Index of corner conected by an edge
What I am trying to achieve with geometry nodes:

Generate curve for each corner of a mesh - Done.
Set start and end points of these curves by positions of Next and Previous edge of a coresponding corner - Done.
Set handle positions of start and end points of the curves - I am stuck on that part.

To compute one of the handle positions corresponding to corner A, I need the positions (and therefore indexes) of the edges A_prev, A_next, and B_prev. I can get indexes of A_prev and A_next with Edges Of Corner node. How can I get index of B_prev edge from index of corner A?

My current setup:
I tried to use the new Corners Of Edge node. My idea was to feed in index of corner A, get index of edge A_next, and get index of corner B by sorting the cornes by distance to the corner A.
This setup works fine, if I plug in some concrete number as an index, but fails, when the Index node is used as source of indexes.
I also tried some setups, where I generate both corners and try to compare indexes, but if I understand, how the Index node functions, these setups run into the same problem as this one.

Is there some way, how to modify my setup or some other setup of nodes, that would compute index of edge B_prev?
Edit:
Example
I am ading images of what I currently have and what I want.
Start with some mesh, e.g. cube.

After step 2, I have this result. (Image includes edges of the original cube)

In step 3, I want to set handles of splines, so the result looks like this - I have problem with computing that. (result was generated with this blender adon: https://github.com/BorisTheBrave/celtic-knot)

XY problem So you want to draw angles between edges?

@MarkusvonBroady I am not exactly sure, what do you mean by angles between edges. I added an example of what I am trying to achieve. I hope, I clarified the question.

It looks like you want to read the other face to access a corner there geometry nodes - Get Faces of Edge

@MarkusvonBroady Yes, reading other face and accessing a specific corner would solve my problem. I can see, how the solution you send can be used for comparing colors or other attributes of a face, but how can I use it for selecting the corner I want?

Turns out that the solution is quite easy in Blender 4.0.0. I am sure, I tried this combination of nodes before, but probably did something else wrong, so I asumed, it was not working.
Solution:

You can see example of usage here:
 Blender 4.0.0 Alpha


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Bone Roll disturbing Mesh Rotation in Pose Mode
When, I done may Weight Paints my Edit Bones are Like this:

But, When I'm creating control bones, I realized that I need to change the roll of my leg bones, But this is disturbing Mesh Rotation in Pose Mode Like this:

Applying Pose to Rest Pose is not working.
I think, I need to retarget weight paint, does anyone know?

Hello could you please share your file (just the armature)? https://blend-exchange.com/

Thanks @moonboots, Problem is Solved, Actually I'm using DEF_ Bones on top of Target Bones.

Oh OK great then ;)

The Problem is Solved, I'm using DEF_ Bones on top of Target Bones.
Next time, I will make sure checking layers, before asking a question.


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Exporting a box with a hole
I'm trying to build a scene in p5.js where a ball falls through a circular hole in a wall. I used Blender to generate a wall (a thin box) with a hole in it by applying a difference modifier to a box and a cylinder. When I load the file to the browser (e.g. using this site, or using p5.js loadModel command), I get a wall with no hole, or with a weird mesh inside the hole instead. This is my first experience with Blender, so I'm sorry if this is an obvious mistake.
Here is the blender file:
Many thanks,
-Matan

You can upload a Blend file here: https://blend-exchange.com/ following the instructions on that page to insert the link into your question. I assume you deleted the cylinder before exporting the file?

Thanks @JohnEason! I haven't deleted the cylinder because when I did the hole disappeared. To make sure it worked I exported the object and then loaded it into a different blender project. It seemed okay because only one object loaded, with a hole in it. But I guess this is where the issue is?

Apply the modifier and delete the cutter. Or, better still, model the hole withoout using a Boolean.

One possible solution is to apply the modifier within Blender. (Note that although you've phrased what you've done as, "applying a difference modifier", in Blender "applying a modifier" is different than an object having a modifier. Currently your object just has the modifier) Use CTRL + A with your cursor over the modifier in the modifier stack.
Alternatively, when you use File->Export, looking through the settings on the right for ones that relate to modifiers. There should be a checkbox that controls whether the modifiers are applied upon export. Ensure that it is enabled.

Thanks! I followed these steps (I applied the modifier. the 'apply modifiers' option was already checked), but the object is still strange when loaded to the browser (https://blend-exchange.com/b/6p4qGXnD/)

(it's not that the modifier is not applied at all, I do get a circle in the center of the box, it's just not a hole)

Ah, I see now. I believe that the issue stems from the fact that the resulting object has concave n-gons. One simple solution would be to triangulate the mesh. You may either use the Triangulate Face operator in Edit Mode or use the triangulate modifier.

It worked! Thanks! :)


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To and fro, or back and forth using sine
I want to make a to and fro motion on x using a sinusoidal equation. I saw it on a tutorial recently but i can't find it again.

Something like the ping pong node
https://youtu.be/9y0HHYD7Lxo

using python? https://blender.stackexchange.com/questions/270888/draw-a-sine-wave-from-a-revolving-unit-circle-in-blender

Add a location keyframe for your object anywhere by hitting I in object mode and choosing Location.
In the Graph Editor select the keyframe for the X value, then go to the properties panel (hit N if you don't see it).
In the Modifiers tab choose Add Modifier > Built-In Function

Click the object's X Location to edit it, and type in #sin(frame/20).
This will create a driver with a scripted expression sin(frame/20) which sets the X location to the SIN of the current frame value divided by 20. Making the cube move on X between -1 and 1 every ~63 frames.

Hello, could you please tell a bit more?

A simple back and forth. Or up-down continuous motion.


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My rigging deforms the body of the character and moves random parts. What did I do wrong? What do I do to fix it?
I'm new to rigging and this is my first major project with it. The goal is to rig my "transformer" body well. However, I'm running into issues with the posing as random parts of the mesh move.
At (0,0,0) is my rigged object. And to its left is an individual part-based object for reference.

Hand dislocated just by entering pose mode.

When moving body parts the body just dislocates.
Blend File: https://drive.google.com/file/d/1nWkBXivnpbU5tIriuGBp0Phm_3gR0hBj/view?usp=sharing

i didn't check more, but your face orientation of your robot is wrong. If fixing that doesn't help, pls upload again [1]: https://i.sstatic.net/O4j8d.png

Hello, could you please tell what part is moving wrongly? Maybe show a screenshot

There's a comprehesive multipart tutorial series about rigging a robot simiar to yours here. It uses Blender 2.8 but the workflow is the same in later versions.

Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues.

@chris how do I fix that?

go in edit mode -> A -> shift-N

As Chris says, first thing, recalculate the normals in Edit mode (select all and ShiftN). For the parts that don't work, select them in Edit mode, remove them from all groups:

Then manually assign to the correct vertex group:


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How to Efficiently Simulate a Push-Broom Scanner (Line Scanner) in Blender?
Hello Blender Community,
I am working on a project that involves simulating a push-broom scanner in Blender. A push-broom scanner is used primarily in remote sensing applications and captures a linear array of pixel data at a time, making it particularly useful in situations where the scanner is moving rapidly over a scene, such as in satellite or aerial imagery, as shown below:

I attempted to simulate this process by creating a perspective camera with very wide but narrow dimensions, like 1500x4 pixels, and used an animation to move the camera over the scene. I render each frame of the animation as a separate image file. I attached the blender file here:

After this, I stitched these 400 individual scan lines together to form the final scan result, using the following Python script:
import os
import cv2
import numpy as np

# Your directory path
dir_path = "/your/directory/path/here"

# List to hold all images
images = []

# Loop over all files in the directory
for i in range(1, 401):
    # Generate the filename
    filename = "scanline_" + str(i).zfill(4) + ".png"
    filepath = os.path.join(dir_path, filename)

    # Read the image
    img = cv2.imread(filepath, cv2.IMREAD_COLOR)

    # Check if the image is loaded correctly
    if img is not None and len(img.shape) == 3:
        # Select only the first two row
        first_two_rows = img[0:2, :, :]

        # Average the rows to get a single row
        avg_img = np.mean(first_two_rows, axis=0)
        avg_img = np.expand_dims(avg_img, axis=0)

        # Append the single row to the list
        images.append(avg_img)

    else:
        print(f"Error reading the image: {filepath}")

# reverse images in the list to get the correct order, otherwise the image would be flipped.
images = images[::-1]

# Vertically stack all images to obtain the final image
output = np.vstack(images)

# Optionally resize the image to correct for errors in the animation (step size, etc.)
# output = cv2.resize(output, (output.shape[1], 500), interpolation=cv2.INTER_CUBIC)

# Write the output image
cv2.imwrite(os.path.join(dir_path, "output-line-camera.png"), output)

If you are planning to use this script, please note that I am using Python 3.10 and opencv which can be installed using pip install opencv-python and numpy which can be installed using pip install numpy.
The script generates this image, which is pretty much what I expected:

Although this method works to some extent, it is significantly slower than I expected, as rendering each line of the image as a separate frame and then stitching them together seems to be time-consuming and computationally expensive. Additionally, the overhead of repeatedly starting and stopping the rendering process for each frame seems to contribute to this inefficiency.
I am seeking a more efficient approach to this problem, ideally something that would allow for the rendering of multiple lines (or even the entire image) at once without the need for post-render stitching.
So far, I haven't found any built-in features in Blender that seem to be designed for this kind of task, and my searches on this site and elsewhere have not turned up any suitable solutions.
Any suggestions for how I might be able to simulate a push-broom scanner in a more efficient manner in Blender would be greatly appreciated.
Thank you for your help.
Additional Note:
Some people in the comments have raised the question how a push-broom camera operates and how the result image would be different from rendering a single image with orthographic camera, so I would like to elaborate on this:
A push-broom scanner captures one line of pixels at a time as it moves across a scene (please also take a look at the blend file I attached), with each pixel in the scanner's sensor array corresponding to a different point in the scene. These sensors are usually paired with a lens system to focus light from the scene onto the sensor array.
Unlike a single image from an orthographic camera, a push-broom scanner can create a unique type of focus effect and perspective distortion due to the continuous motion and line-by-line capture method. While an orthographic camera captures the entire scene at once from a single point of view, a push-broom scanner's point of view changes throughout the scanning process. Please take a look at the following image which is capturing the same scene using a perspective camera:

And here is one image of the scene rendered with an orthographic camera:

Also note: As shown in the .blend file, the captured data (objects in the scene) are not moving.

It might be helpful to people trying to help you if you uploaded an example blend file to the site https://blend-exchange.com and add that link in the question.

also a link to a push broom scanner would be helpful. You want help, right? so if i were you, i would make it as easy as possible for those, who help you for free in their free time instead of letting them google on their own. This would attract far more people - and as you can see - until now - you attracted no one to your question.

Is the  captured data moving? (i.e. the dark blue pixels are an update of changing input, the light-blue lines are a record of the last dark-blue sample)

How do these scanners work? Does the array of sensors have a lens? How is the result different from rendering single image with orthographic camera? Can you show us the desired result of an image?

You can get all kinds of weird funky "camera sensor" effects by baking completely glossy material.

Here is the blend file:

You probably want to disable shadows for the baked object and also you should keep color management in mind. I don't think baked textures use the same color management settings as render by default. I would choose 32-bit float option, when creating the image

And then after baking it can be saved as 32bit EXR containing untouched data from render and then you can hit that View as Render checkbox in the image viewer to view it as a render:

Thank you for your suggestion.
I am trying to understand how the baking of a completely glossy material could help simulate a push-broom scanner effect. Could you please elaborate on your idea? Specifically, how would this technique allow for the capturing of individual lines of a scene as a push-broom scanner does?
I appreciate your time and any additional information you can provide to help me understand this method better. I am particularly interested in whether this approach could improve the efficiency and reduce the rendering time.
I am looking forward to your further guidance.

You can use any object as a camera then(as a camera sensor of any shape). It bakes the surrounding scene according the UV map of the object. I have no idea how those scanners work, but if you have an array of light sensors and then some sort of lens, it will produce some sort of perspective, but since every line is captured only when it moves, there would be no perspective(or maybe different perspective?..) in that direction. If you don't care about any perspective, then use a simple Orthographic camera.

I just noticed, you talk about that in the edited question. So, I think this is exactly what you need. You can simulate a lens by curving the object so it takes light from multiple directions in one axis, but only from directly below in another, like the scanner would. You can also have the object extend physically in your scene in a path the scanner would move in. I don't know how this would work with a scene that is not static though...

Thanks, I understand better now and this gives me a new line of thought. Is my assumption correct: baking onto a flat plane result in an orthographic projection? If that's the case, I assume we might be able to adjust the surface's geometry and curvature to simulate the desired effect.
However, I noticed that the example images you provided appear somewhat distorted (first image, bottom right). Is this a typical outcome of this method? How can this be avoided?

I just saw your other comment: That sounds very promising. How could we address the small distortions in the result image?

Oh, that one had the baked object shaded flat, so it was as if the camera sensor was made of lots of flat faces. No problem at all - just shade the object smooth. It might make sense to have denser geometry to approximate curved surface more accurately with polygons. I'll add a blend file in a couple of minutes.

I added a.blend file with very exaggerated wide lens effect.

Thanks! The example was very useful in understanding this method. I realized that an alternative "camera" or rather image capturing device can be crafted and by being very careful and thoughtful about the geometry of the surface, I was able to recreate the desired result with a greatly reduced render time. However, there are some limitations compared to a standard blender camera, like depth of field for instance. Also it seems a standard camera is much easier to control.
I was actually hoping to find an approach that would allow me to render images from several cameras at the same time.

Depth of field is possible to simulate. You can render a depth "pass" by replacing all materials(except the glossy one) in the scene with one that would display distance to the baked object... Rendering animation will be tricky because it's tricky to write a Python operator for that. You could try asking about this in separate questions.

You could have a look at add-ons automating baking. There are many. You could see their code... But yeah. This is getting to be quite some work that I guess would pay off only if you have to render quite a lot of these renders.


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Set curve radius has no effect on my hair system (3.3 to 3.5)
I followed many tutorials on how to create hair in blender with the new geometry nodes system.
At first when I create my first strands, their radius is way thiner than the ones everyone is supposed to.

And when I try to change the radius nothing happens.

I tried other nodes in order to see if the problem was coming from my node tree, but it seems not

I also tried the "Set Hair Curve Profile" node which neither has an effect.
It is the first time in my 2 years of learning blender that I got really blocked without finding an already existing solution.
Thanks a lot for your help, hope any of you could do something
EDIT_1 : I created this same node system on 3 different computers, they all have the same problem. Is there a prerequisite or a button I did not checked ? Don't hesitate to try the simple node tree on your own computer
EDIT_2 : I still can make a geo node group at the end to convert my hair to mesh and change the radius of my profile curve circle. But I loose all the interest of working with curves and my computer bercomes really laggy

From my experience (using the interface particle hair system) changing the root and tip radius affects the simulation, and perhaps the rendering, but you won't see the radius in the 3D view. Do you see a radius change in the tutorials?

Yes, normally it is supposed to change the radius in real time but it doesn't in mine even in rendered view. I still can convert my curves to mesh and change the radius of the circular curve profile but it costs me a lot of ressources. It is not supposed to work like that.

Have you set Curves > Shape to Strip in the Eevee settings? (or Curves > Viewport Display > Shape for Cycles)

Yes, you can look under "shmuel" answer

you have to change the viewport render settings from strand to strip.
it's in the render settings (same place where you set the noise threshold, denoising, l8ght bounces etc.) under viewport.

I tried to change the viewport render settings from strand to strip and the change is indeed visible. However when I render my modifications are not applied, thanks for your answer

There is a limitation if you join another bezier curve object with the curves. Depending on the order of the joined geometry the radius can be messed up. See #99786 But your first simple example works for me in Blender 3.5, in the viewport and rendered with Eevee.

Ok It indeed worked. I thought I already tried the option once. Isn't it weird that it is labeled as a "viewport display setting" ? Thank's for all, it also works in cycles. You helped a lot


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How to parent eye armature to head bone in body armature
I'm following this tutorial on Youtube.
At 4:22, he somehow parents the eye armature to the head bone in the body armature. He doesn't actually show how to do it but uses an analogue by copying a bone and moving it where the head bone would be.
I select the body armature and then shift select the eye armature and go into edit mode and follow what he is asking to the best of my ability but there is no option for "keep offset" when attempting to parent. I does not function the way it should. Is there a correct method?
Also while I'm asking, would a similar method be used for parenting say teeth to the head bone? Thanks.

You can set the parent of the bone in the Bone Properties>>Relations tab.

Your question sounds like you have two different armatures (which are objects), you're selecting both and then entering edit mode (which in this case will be a "double" edit mode, working simultaneusly on two different objects). But the parenting you're looking for is possible only internally to one single object.
So, select the eye armature, shift select the head armature, press Ctrl J (join two objects into a single one).
Then select the new object (armature), enter edit mode, select the eye bone, shift select the head bone and press Ctr P (keep offset).
And, yes, teeth and head can be treated in the same way (create the new bones in edit mode with shift A or Shift D).

This makes sense to my however when I press Ctrl j and attempt to join the armatures, the eyes disappear. If I Shift select them in the opposite order, body disappears. Am I missing something? Each mesh is already has weight painting applied.

Delete the armature modifier from the mesh, then join, then re-add the armature modifier choosing the new object as target. You won't loose your weights.

Thank you very much!


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PBR transparent fence texture node set-up not working
Thanks in advance for your help!
I'm working with a transparent wire fence PBR texture, and I cannot get the space between the wires to be transparent. (I've also tried on a simple plane mesh - same results)
I've tried with two different materials:
Picture 1: https://www.texturecan.com/details/134/
Picture 2: https://cc0textures.com/view.php?tex=Fence06
What am I missing here?

Have you tried individually selecting the "in-between" wire faces in edit mode and applying a transparent modifier to them individually?

on your "right panel" (just under the option "backface culling"), on "blend mode", it is set to "opaque". As you are using Eevee, click there and just choose another blend mode, like "alpha clip" or "alpha blend".

other settings that you may need to pay attention when using PBR under Eevee are:
Render → Screen Space Reflections ON;
Render → Screen Space Reflections → Refraction ON;
Material → Principled BSDF and Transparent BSDF into Mix shader;
Material → Principled BSDF → Transmission 1.000;
Material → Mix shader Fac mostly all the way to Transparent;
Material → Settings → Blend Mode Alpha Blend;
Material → Settings → Screen Space Refraction ON;

That worked! thank you MCunha!


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NurbsPath causes object to rotate when specified in Curve modifier. Not seeing why

I'm following a 2.79 tutorial with a 2.8 release.
At one point the video is trying to curve the blade using a Path and the Curve modifier.
I've tried moving the origin points of the blade object and the path to the same place in 3d space but it's still rotates the 3d object 180 degrees in Object mode.
I'm not sure what I'm missing here. Can someone help?

You rotated the path in object mode!
Apply rotation to your path and blade if needed.
Check the origin, in your case looks fine, path and Blade should be at same location.
Also in your case looks fine, but paths arrows should look in the direction you want to let follow objects.


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transparent instead of solid grey models?

I'm new to Blender, and I think I accidentally pressed something to turn everything into this transparent point only mode instead of solid grey models. Could someone explain how to change it back? Tysm in advance! Sorry if this question has been answered before, I just can't find it probably because I am describing the problem very badly.

You may have clicked transparency in the viewport next to one of the four viewport shading spheres. To set transparency off, press ALT+Z. This will disable it.
You currently are in wireframe also, so click on the shader sphere next to wireframe if you want to go to a different view.


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Animated particle texture linked to particle age
Is it possible to create a particle system emitting objects onto which there is a video clip as its texture, with the video clip starting from the beginning of the clip, on each particle when the particle is spawned.
Currently they are all in sync, regardless of when the particles were spawned.
I'm using 2.91.
Thanks.
Matt

Not without scripting or doing a whole lot of tedious work-- you need a separate image texture for every frame of the film.  Blender is not designed to load an entire video in a single frame, because the memory use would get out of control really, really fast.  It loads only the exact frames you tell it to load.

Soooo basically as the video plays (and the animation), the particles' textures change? I think if you give the initial emitting object an image (or for our purpose a video) texture on a generic principled BSDF shader, the particles color will correspond to the color of the part of the texture it was emitted from.


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How do I get a Roblox Stormtrooper helmet to not be greyed out?
When I insert an .obj file from Roblox Studio, it greys out the Helmet. Does anyone know how to fix this?

Do you have a material for the helmet? If not, the default is gray.

I do have a material, it's plastic. Is that default?

It turns out it was smooth plastic, but it worked for other helmets. I tried to use ice but that didn't work either.

Check the materials tab on the right for the helmet. Look at the material preview for it. The problem may be the lighting, as the helmet, if glossy metallic, might just be reflecting the world light.

Sorry, I am new to Blender. Where is the materials tab? Also I inserted the body and the Helmet as 1 object.

There are a few reasons why this could be happening.
Listed as follows are some, with their solutions.

You are using EEVEE renderer instead of Cycles.
Change this by going to the Render properties tab, and setting the renderer to Cycles.

You don't have a material set.
Go to the material tab in the object properties with the object you want a material set for selected, and add/adjust your material.

You need to adjust the material set for your object to something other than the default.
In the images, I try to achieve a material somewhat like a stormtrooper helmet.
First adjust the roughness, then adjust the metallic-ness of the Principled BSDF.

I believe you are doing this already, but it is always good to *Compare your object material to another object in the scene, with Rendered view selected.
In these photos I compare the cube object with the helmet material to a blue Suzanne "monkey" head. (Also with a principled shader.)

With no shader adjustment:
With roughness set to 0:
With final material:
One last tip: Adjusting world shader can sometimes give you a better preview of your materials. Here are examples of world brightness and color with a scene of objects with the helmet shader:
Sometimes a dark world background with a bright light helps too:
I hope this helps!

TYSM! Just saw it and I'll try all these different ways! I can finally finish my job.

I have tried everything you told me to do, but it has not changed. When I changed it to cycles, it just became more blurry. When I changed the material it stayed the same. I changed the roughness and nothing changed. I did all of these together and it doesn't even it was just really dark. Thanks for trying to help though.

Interesting. Could you give a link to the .blend file? I want to work with it.

How would I do that?

Simply upload it to https://blend-exchange.giantcowfilms.com, and copy-paste the link provided into your question.

Ok, I'm nearly done.

I forgot to press upload after I put everything in was wondering why it wasn't uploading xD. I have done it now and the file should be ForNate.blend because i had no other name. Here it is

I am not sure why you are not able to change the color of the character. I could. One thing though that I noticed was that the entire character is one mesh, and has different materials assigned to different vertices within itself. You can try going to edit mode and selecting a face on the helmet, then editing the material attached to it. This is all I can really offer to help, alongside with the answer I provided, for I do not see any plain issue with the character's material.

Could you send me a link with your coloured Stormtrooper, I want to see what you did and also use it maybe to help my one out.


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How do I create a drop-down menu with custom properties? (Blender 3.5)
I want to create a drop-down menu for my rig. I have this settings bone in it, in which I want to add something to change the subdivisions. I thought integers aren't that user-friendly, so what I thought would be a good idea is to make a drop down menu (a bit like a video game settings menu).

This drop down menu would allow you to change the quality of the rig along with the 3 options "Low", "Medium", and "High".
The thing is I don't really know how I would do this and I can't seem to find any answers online, so I'm completely stuck. What do I do?

You can create all kinds of custom UI elements through Python. This Stack Exchange post is one of the best I've seen on the topic:
How to create a custom UI.

would that work in a custom property though?


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When I add a subdivision surface modifier it creates spikes at the loopcuts

I am making a character model with a cylinder as its base. When I add a subdivision surface modifier it smooths out a lot of it but it makes the body smaller around and creates tiny spikes where I put loopcuts.

Hello, maybe you have inner faces?

You probably have normals that are inverted. Check them by enabling Face Orientation overlay:

f
You can select faces and hit  Alt   +   N   ->   F  to flip normals.

You could also select everything and use Recalculate Normals  Shift  +  N , but that algorithm will chose normal direction randomly when you have some types of geometry like floating planes or anything else it cannot "understand".


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Importing a standard color into blender (gamma correction issue?)
I'm having issues with rendering exact colors. So I'm working on an archviz project and there are certain objects that require a specified standard color. Basically the color on render has to match the color on the standard very precisely. My issue is, that if I were to copy rgb values, the rendered color would not be the same (due to gamma correction I assume). I've found online that setting color management to standard will fix the issue, but doing that jeopardizes the photorealizm.
So in my specific case I've been told to use a color from NCS. It's a standard color, which has the following properties:

By simply pasting the hex values into blender will output wrong colors:

So I understand that light will also interact with the material and make a difference, but I need to make the base color in Blender to really match standard color. What are the options? Is there a way for me to manually convert color from sRGB to linear space so it still looks the same when in Blender? What are the possible workarounds?

"doing that jeopardizes the photorealizm" - you can't eat a cookie and have a cookie. The sRGB/filmic is a transformation happening at the very end of the pipeline, so either you want the colors distributed in linear fashion (the energy of light), or in sRGB fashion (shift the colors so that e.g. 20% darkest colors take 50% possible values) or Filmic fashion (squeeze hell lot of very bright colors into the saved range).

As I understand your problem, you want to render as you already do, but you want to achieve a particular color on a particular surface in the output file. Kind of like achieving white color in filmic means setting the value of the color (each channel value) to its celing value 16.291740238…. So you need to apply a reverse transformation on your color and input that as the value, correct?

More reading: https://blender.stackexchange.com/q/46825/60486

Yes, I'd like to reverse transformation my color and input that as value, which will allow me to use filmic for better photorealizm and at the same time make the color accurate (there will be color variation - darker and lighter because of bump, which is completely fine)


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Subdivision surface modifier issue in Blender Guru Chair tutorial
I am new to Blender and while I was doing Blender Guru Chair, I came up with the following issue. Can someone help me out?

This is not an issue, or at least I don't see an issue. The orange part is the original geometry before it's modifier by the modifier. Some of it is closer to the viewport camera than the resulting geometry, and that part is visible.

Is the merge not catching, in a Mirror modifier? Please give a closer description of what the 'issue' is, and an illustration more indicative of it?

I agree with @MarkusvonBroady. This is the same effect that you saw in the question you asked earlier: https://blender.stackexchange.com/questions/295971/how-to-remove-this-extra-edge-extrudes-outwards-along-the-entire-shape-in-blende where I requested that you share your Blend file so that I could confirm my suspicion.

@JohnEason Hi John. After that 1st one came down with an issue I tried to do it again as new project and then got stuck with this issue. I'll upload this one as well.

@RobinBetts Hi Robin, I'm sorry but I'm actually I'm new to Blender. So I don't even understand how to describe this issue.

I haven't looked at Andrew's tutorial for a couple of years so don't know if he mentions it in the tutorial, but you don't have clipping checked on the Mirror modifier panel which means that the two halves of the mirror aren't merging properly.

There's a slight tear along the mirror plane, where, in places, vertices have not merged as requested in the Mirror modifier.
Unless otherwise instructed, the mirror-plane passes through the object origin. (The little orange dot.) Some  of the vertices that are supposed to be on the mirror-plane have wandered off it during modelling.
Some steps to fix:

(Keyboard .) > set your Transform Pivot Point to '3D Cursor'
In Object Mode, with the chair selected, ShiftS > 'Cursor to Selected'. That will put the cursor on the object origin.
Edit Mode again, ShiftAltLMB select all the the loops, inside and out, that are supposed to lie on the mirror plane.
SX0. That will flatten all the selected vertices onto the plane through the object-origin, and then they will be close enough to one another for the 'Merge' on the Mirror modifier to catch.


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How to remove this extra edge extrudes outwards along the entire shape in Blender Guru Chair tutorial?
Hi I'm new to Blender and while I was following Blender Guru Chair tutorial I noticed an edge/face is extruding outwards from the outer and inner edge of the chair base even though there are no any vertices or mesh extended to that area. Is it normal or is there a way to correct this? Thank you.

Please share your Blend file via https://blend-exchange.com/ following the instructions there to paste the link into your question.

@JohnEason Hi, thank you for trying to help me out. I just added the file just like you asked.

If you go into Edit mode, hit the A key to select All and hit G then X and drag the mouse to the right slightly the overlaps should disappear. The effect appears because the two halves of the mirror image are overlapping.

Once again, your geometry has drifted away from the mirror-plane, which goes through the object-origin.
If you move geometry in Edit Mode, you do so with respect to the object-origin. Perhaps you have done this to align the model to reference? If you did, you moved all the vertices, but left the mirror where it was, so as @John Eason has commented, now the reflected halves overlap.

Edit Mode: select one or two vertices that are supposed to lie on the mirror-plane.
ShiftS > Cursor to Selected
Object Mode:  Header > Object > 'Set Origin' > 'Origin to 3D Cursor'

Now the object origin will be back on the desired mirror-plane, with respect to the mesh.
If you need to adjust the object to reference, do it in Object Mode. That will move the mesh's 'vehicle', the object itself: (its origin, therefore the mirror) .. and carry the mesh along with it.

It's from your mirror modifier most likely. try turning it off and see if it gets rid of it


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Pinching problem

So I have a 3D model with the following problem - one vertex is kind of holding too much topology in once. I am not entirely sure as to how I can fix this pinching issue (maybe separate it, but how exactly?).
With Subd:

Without Subd:

Hello, what do you mean by "holding too much topology in once", maybe show your reference object?

The selected vertex on the images above is problematic - I need the left part (which has to be separate from this vertex and should have its own vertex) to be a bit on the left, without being connected to the right part (because else if I try to move this one vertex, the whole thing moves). In other words, I am trying to add another vertex which would act as a separator between these 2 parts of the 3D model and hold the left part so that I can move it freely

Your tomology is messy, maybe show your reference object

Sorry but I don't know as to what you mean by reference object. Do you mean the .blend file? I have put it in the post for it to be downloaded (but if you mean the concept art, I don't have such)

I mean do you have an image of the real object that you're trying to model? Your topology is very messy, maybe model it another way?

Nah sorry I don't really have an image. Idk if it makes it clearer, but I'm trying to make the selected vertex from the photo to NOT stick to the right side of the 3D model in the pictures above


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How to make a plane mesh double sided?
I have a simple pingpong table model. I use a plane mesh for the net part, but one side of it appears invisible when imported in unreal engine. Ive seen guides on how to fix it but they only show them on cubes. Flipping the red face literally flips the plane so either way 1 side is still invisible.
How to actually achieve a both sided plane mesh? For my case, I want both of the sides to be in white color
Image of my model:
EDIT: I have applied the Solidify modifier and it worked!

How did you do it, did you use an image or is your net modelled, with holes? In that case you can simply extrude it to give it thickness

Yeah its with holes, Ill try that next time im on pc. However not sure but I think I tried it once and it didnt let me add any thickness

Maybe show a screenshot of your object or even share the net object itself

As @moonboots says you should be able to simply extrude it slightly to give it some thickness. Make sure you recalculate the normals (Shift-N in Edit mode) when you've done it though because it's possible to extrude a plane 'in the wrong direction' so that all the face normals are pointing the wrong way!

In unreal, there should be a "Two sided" option in the Material Editor (Main material node - Details panel). If not, there should be a no cull option for backfaces somehwere.

Ok I added a screenshot of the model. I tried extruding but it didn't work. When I select it in edit mode and try to flip, it still flips both sides which mean the other side is then wrong. Can't really do the two sided thing in unreal because I'm exporting the model as one, with all objects connected already. As for no cull option in blender, it simply shows me that one side is invisible. I applied solidify modifier to the plane but I'm notsure what it did.

Is this, at heart, a question about Blender? As @Christopher Bennet has already said : https://www.youtube.com/watch?v=s5qv0YBCE88

Solidify is the same as extruding, also, when you'll export to Unreal, you'll need to apply the modifier, so you just needed to extrude, and make sure that the faces were correctly oriented (Shift N to recalculate)

you can add a "Solidify Modifier" to the plane and check "Apply Modifiers" in the export options.

This worked for me, however the other side is now darker in color. Is this due to the angle/camera? Or is this a common thing and I need to change something?

@SimpleBoy Hello and welcome. This site is not a regular forum, please don't reply "Thanks" as an answer or comment, instead upvote the post that helped you. If you feel it completely solved your issue consider marking it as accepted.

I didn't say "thanks", I even asked a additional question.


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I need the node texure image sequencer but i cant find that
Can someone help me please?
I need to put the image texure sequence but i can't find that in the shader editor

https://blender.stackexchange.com/questions/186911/blender-2-8-how-to-use-image-sequence-as-a-texture

There isn't a Texture Image Sequence node, it's actually just a Image Texture node in which you load an image sequence.
If you press ⇧ ShiftA in the shader editor, under the Texture category, you will see Image Sequence in second position:

This will open the browser for you to select the first image of the sequence. Once you click the Import Image Sequence button, it will create an Image Texture node set up to read a sequence:

You could also just add an Image Texture node, load the first image of your sequence, change the Source parameter from Single Image to Image Sequence, adapt the sequence settings to yours and it would work the same. But it's faster with the other method ;)

You can use the Image Texture Node to play a Video/Image Sequence in a Material. Don't forget to set the Frame Count according to your footage, otherwise it will only show the first frame.


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How is the mapping between screen space and camera coordiante system in blender
I was referring to this link to understand how to decompose a projection matrix. It says that screen space can have a different coordinate system than the camera, even scratchapixel  says the same. But I do not see any documentation in blender about it. How is the mapping from camera coordinate system to screen space in blender?
Is it as shown below,  or
Or is it something different than both?

Please clarify what you mean by "screen space" and "camera space". How do you obtain those values? For example in shader nodes there's "Texture Coordinate: Camera", and "Texture Coordinate: Window"

@MarkusvonBroady screen space would be the coordinates obtained after performing projection from camera space. The scratchapixel link I provide explains it with visuals if that's helpful.

How is your problem related to Blender?

@MarkusvonBroady Each software can do this mapping according to their definition. I could not see any documentation how they do it in blender, I wanted to know how it is carried out in blender.

It is preferred here to try and explain your issue within the question instead of relying on external links, which might expire and make this question useless. Also it would be nice if we would not have to read through all the text for understanding. Is your question more or less if Blender sees images from bottom left to top right or the other way round?

The issue here is, this website is to ask questions about Blender. And the way you state your question, it's unrelated to Blender. Yes, such coordinate spaces (or similar) exist within Blender, but just like BSE is not the best place to ask a question about linear algebra, even though linear algebra is used by users and devs of Blender, asking about such concepts, is not best either. If you presented a real problem in Blender, solving which requires some explanation on differences between texture coordinates, then yes, it would be a valid question per this site rules.

@MarkusvonBroady I believe this is a valid question to ask here, as it pertains specifically as to how blender does this mapping.

@GordonBrinkmann the link was supposed to be an additional context. The image I gave provides the information regarding my question

"I believe this is a valid question to ask here, as it pertains specifically as to how blender does this mapping." - the reason why I think otherwise is that you couldn't answer my question on which coordinate systems in Blender do you mean specifically. If you clearly pointed to two coordinate systems in Blender (and I ask how you obtain them), then yes, this could be explained (and therefore the question doesn't need much to be a good question). But as it is phrased currently, we have to guess what you mean (and there's actually nothing to guess, you don't actually use those in Blender!)

@MarkusvonBroady Although I wrote an answer which was accepted, I totally agree with you on this matter.

@MarkusvonBroady I believe you are right, it seems that concept is not used in blender. It is still strange as it is part of generic computer graphics pipeline. Therefore I am deleting the question as it could be misleading

The scratchapixel link might provide useful information, but I'm sorry it is too annoyingly much to read just to figure out what your question is. As I understand it you basically want to know if the coordinate system of an image viewed/rendered by the camera is going from bottom left to top right or top right to bottom left? Well, it is from bottom left to top right.
If you want to move something in compositing to the right, you have to move it in +X direction. Moving upwards is +Y direction. Also the coordinate system's origin is not in the center of the image but the bottom left as you can see in these examples:
Using a Sun Beams node in the Compositor, by default it is set to create sun beams starting at X = 0.5 and Y = 0.5, and in the screenshot you can see these beams starting from the center of the image, there is also a cross indicating the position if you have selected the node:

Setting the starting point to X = 0.0 and Y = 0.0 moves it to the bottom left, X = 1.0 and Y = 1.0 is top right:

Another way to see it with the rendered pixels is when you right-click with your mouse on the rendered image. While holding the right mouse button down, the status bar indicates the X and Y of where your cursor is positioned, going from X = 0 and Y = 0 in the bottom left corner to X = 1919 and Y = 1079 if you rendered an image with a size of 1920 × 1080 pixels:

Also the 2D coordinate system of the UV Editor goes from bottom left (0, 0) to top right (1, 1):

If this is not what you are asking for, then I need more clarification in your question.

Thank you, this is what I was referring to, I believe that (0.5, 0.5) in your example refer to the screen space.

@ssuraj I do not believe (0.5, 0.5) refers to screen space, I actually do not understand what screen space is in this context. In your scratchapixel link the term "screen space" is used exactly once and is said to be used synonymous with "canvas", which is more or less the image plane. So the "screen space" is the rectangular area of the image between (0, 0) and (1, 1). Of course the "screen space/canvas" has a different coordinate system than the camera, because it's always 2D starting at one corner to the next, while the camera can be moved and rotated in the 3D space of the scene.

@ssuraj You're starting some sort or semantics discussion. Imagine that you asked »What is a difference between a "figure" and a "shape" in Blender?«. Upon our questioning where in the interface you see those terms you would say you don't, but those are terms common in software, and you wonder how it looks in Blender. Once someone assumes what you might mean, you ask »oh so is that what a "shape" is?« In the end of the day, a "shape" is just a word. Sure, linguistic prescriptivism exists, but semantical talks aren't a good fit for BSE…


text:
Blender rendering repeating same frame over and over
When I started rendering an animation it kept using 1 frame for every frame and sometimes it renders blank as well. I am rendering on cycles, but it is also rendering instantly and when I put it on eevee it goes on cycles quality.

"it kept using 1 frame for every frame" is unclear.

I meant the same frame was repeated for every frame when rendering

Most likely this is because you have an image sequence/single image in the video editing tab of Blender. Simply delete this strip, and your animation should render correctly.
This would explain the black frames, repeated frames, instant renders, and cycles-quality renders when set on EEVEE.

I guess I did have an image there. Seems to be working fine now. Thx.

If this answered your question, please accept it as to help future users

THANK YOU
The Editing Mode would have been the last thing i thougt of, trying to find the problem with my render settings...
This is such a vital information and I searched so long for this answer >-<
This is definetly something for the "fix" suggestions for future blender versions.


text:
MULTIPLE RTX 2080 GPU's in Blender 2.9 not being utilized
First up, I am a complete noob when it comes to Blender, so I apologize in advance if I am asking rookie questions.
I am a specialist box builder for the pro level film & video editing industry. I have just completed a build for a client at FOX STUDIO'S in Sydney who uses Blender heavily.
The specs on the machine are as follows:
Thread Ripper 3970X
128 gig ram
2 x Nvidia  2080 Super
Samsung NVME 970 EVO+ 1TB systems drive
2 x Force MP600 series Gen4 NVMe PCIe M.2 SSD 2TB in raid 0
Corsair 1600W AXi digital PSU
Win 10 pro
TRX40-E ROG STRIX RTX40-E-GAMING MB
water cooling, etc.
I installed Blender V 2.9.0 It is seeing and recognizing the 2 x Nvidia GPU's and allows me to select them for the rendering choices, however regardless of the settings that I choose, Windows is only showing 1 x RTX GPU being used. I can get it to use both the CPU and 1 x GPU at the same time, but no matter what I do, I cannot get it to use both GPU's at the same time.
Is this a Blender bug, or am I missing something critical? a setting or driver?
Any help would be appreciated.
Kind Regards
Colin. R. Selby
Eye Candy Labs.
Sydney, Australia

I think this might be of use to you.
https://blenderartists.org/t/eevee-multigpu-yes-you-can/1195530

Have you bridged the GPUs to with an SLI cord to act as one?

They should not be linked in SLI!

Are you rendering a scene that is complex enough to use the GPU significantly? Try using one of the scenes from the blenchmark. Set blender to use gpy only, you should see only two tiles being rendered simultaneously.


text:
How do I render my nodes on this video?
I attempted to overlay a person's face with a mask I set up my composite nodes, but it just will not render it at all
If you could help me out that would be so appreciated

https://blender.stackexchange.com/questions/174215/how-do-i-animate-an-image-in-the-video-sequence-editor-to-match-the-underlying-v/188346#188346

https://blender.stackexchange.com/questions/183081/how-to-have-person-in-video-mask-added-geometry-as-they-walk-in-front/183108#183108

https://blender.stackexchange.com/questions/65007/overlaying-an-image-to-cover-a-face-in-a-video

@susu hi Susu, i used that exact guide to make it but it still does not work :(


text:
Collada exporter generates too many UVs
I have a model with only 98 vertices. When I export it to Collada with Blender 2.64, it generates a Cube_001-mesh-map-0-array with 768 entries, that is, 384 UVs. I've checked the UV map, but it doesn't complain duplicates, so I don't understand why...
I tried updating Blender to 2.69 and now it got worse. When I export it now I get 1152 entries, 576 UVs.
Is this the expected behavior? I am trying to keep the vertex data to a minimum for my game, but this doesn't help...
Edit: I just realized that the difference between 2.64 and 2.69 is that now all the polygons are triangles instead of quads, so it seems it adds more UVs to cover them... But I debugged it and there are many duplicated UVs. Shouldn't it just point to the same UV index, instead of duplicating them?
Edit2: I created a ruby script to remove the redundancies: https://github.com/endavid/headerify/blob/master/bin/headerifyCollada.rb

Read about UVs being per-loop: http://blender.stackexchange.com/a/6710/1363

Thanks :) The thing is that I have a simple model that uses spherical projection for the UV map, and I still get too many UVs. I created a script to get rid of the redundant vertices, and now I managed to reduce the number of {position, normal, uv} vertices from almost 400 to just 100 :) This is the script: https://github.com/endavid/headerify/blob/master/bin/headerifyCollada.rb


text:
Is it possible to generate a mesh from a armature
If I make an armature like this:

Is there a way to automatically generate a mesh to go on the armature?
to make something like this:

Use the "Skinify Rig" add-on.

I just looked for this too... no Joy.
Wrote my own.
import bpy
import math
import os

Meshname = "armature_mesh";

def convertVector(v):
    return [v.x,v.y,v.z]

def main():
    #make sure what we're going to work on is an actual armature.
    if bpy.context.scene.objects.active.type != 'ARMATURE':
        print("Active object must be an armature!!");
        return 1;

    theArmature=bpy.context.scene.objects.active;

    #delete any previous attempts
    if bpy.data.objects.get(Meshname) is not None:
        bpy.ops.object.select_all(action='DESELECT')
        bpy.data.objects[Meshname]
        bpy.data.objects[Meshname].select = True
        bpy.ops.object.delete(use_global=False)

    #time to copy the armature to mesh
    #define our data containers for the new obj
    Verts=[]
    Edges=[]
    Faces=[]

    #select the armature and enter edit mode, and get all the bones.
    bpy.context.scene.objects.active = theArmature
    bpy.ops.object.editmode_toggle()
    bpy.ops.armature.select_all(action='SELECT')
    bones = bpy.context.selected_bones

    #loop through the bones, putting all the coords in the data containers.
    for bone in bones :
        Verts.append(convertVector(bone.head))
        Verts.append(convertVector(bone.tail))
        VertID = len(Verts)
        Edges.append([VertID-2,VertID-1])

    bpy.ops.object.editmode_toggle()

    #make the object and add all the data.
    mesh=bpy.data.meshes.new(Meshname)
    mesh.from_pydata(Verts,Edges,Faces)
    newMesh=bpy.data.objects.new(Meshname,mesh)
    bpy.context.scene.objects.link(newMesh)

    #connect the connected bones by removing doubles
    bpy.context.scene.objects.active = newMesh
    bpy.ops.object.editmode_toggle()
    bpy.ops.mesh.select_all(action='SELECT')
    bpy.ops.mesh.remove_doubles()
    bpy.ops.object.editmode_toggle()

    bpy.ops.object.modifier_add(type='SKIN')

main();


text:
Where is the operator panel in Blender 2.8?
The tutorial I read is based on 2.79. So I'm not sure if it's still the same name in 2.8. But I can't find anything providing similar functionalities.

Blender 2.8 onwards the default shortcut to access this is F9 not F6.

It can be found in the 3d Viewport:

As well as in the Edit menu where it is called Adjust Last Operation now, where you can also right click it and choose Assign Shortcut if you wanted to be able to call it with a keyboard shortcut like it was with F6 in previous versions:

Obviously, it does not need to be F6 and could be anything that is convenient to you.

This is very similar to How to reduce poly number when you start creating object in 2.8? , however I think the question is formed a lot clearer so I think it makes sense to have a clear question and answer here to be able to link all the possible duplicate variations of it in the future.


text:
Does Blender no longer support Make Human file format?
Does Blender no longer support the use of Make Human file format MHX1?
The file type is changed from mhx to dae and the mhx file type no longer shows up in Blender as a supported file type. I mention this as I see some creators
point out the changing of Blender settings in their tutorial videos that no longer match the current configuration and it makes it more confusing .

The MHX1 format is extremely old and has been deprecated (in favor of MHX2) for many years. MHX1 should not be used, and no modern version of MakeHuman supports it.
Contrary to MHX1, MHX2 is an add-on that needs to be installed. It is not bundled with Blender.
How to get MHX2 support is answered in a MakeHuman FAQ, see http://www.makehumancommunity.org/wiki/FAQ:What_happened_to_the_MHX_export_in_MH_1.1.x_and_later%3F
Quick summary:

In a Blender + MakeHuman 1.1.x setup, you need to install MHX2 from https://bitbucket.org/Diffeomorphic/mhx2-makehuman-exchange/overview
In a Blender + MakeHuman 1.2.x (currently in alpha) setup, both the MH side and Blender side of MHX2 are shipped with the MakeHuman zip.

thank you have been working the problem and will take all the advice I can get

on a semi related topic if you go to the makehuman side ,http://www.makehumancommunity.org/targets.html   To get the full effect of MakeHuman go to the targets page ,
( these are all slide modifiers too add to makehuman  , add them to :
your PC: C\user\your AKA\documents\makehuman\v1\data\custom ,
it will add a huge amount of functionality to the makehuman  creation side. Please note I downloaded the program and unzipped it to a folder on my desktop and after using it it placed a makehuman file in the above location where the program is drawing its information from.

As pointed out on the Blender side ,left click upper left corner for scroll down menu .pick user preference ,Ctrl\alt\U ,go to center tab user panel,
pick add-ons, add files and activate with check , save user preference , go to
makehuman side find plugin folder add plugins.have loaded the files into 3
zip files per file  in a master file for Blender and MH side for anyone that wants them and are having a problem getting them just email me ,they cover MHX2 and DAE , thanks all.


text:
BGE Strange white artifacts on edges of objects
I just baked all my cycles materials onto my objects for a game i am making, but in the BGE there are strange white artifacts on some of the corners and edges of my model... I really have no idea what is causing this, so i am sorry i can't tell you more.
Here is a link to download the .blend --> https://www.mediafire.com/?5hhsfr4hdmkabf2

Could you add a screenshot of the UV/Image editor in which the interested part is shown?

My guess is teh bake margin got interrupted.. Check your bake settings and rebake.


text:
add object at specific location with python?
This might be a really stupid question-I'm working in bpy right now and want to add a plane at a specific location...I know that How to add an object at a specific posistion in Blender Game Engine works for bge but am not sure if it'll work in bpy...

The tooltip of the Add > Mesh > Plane menu path shows this information, press Ctrl+C to copy it to clipboard.
Tooltip

All of these menu items trigger operators and take several optional arguments, location=(x,y,z) included. The same applies to the other items in the Curve, Surface Metaball etc., menus.
Docs
The total list can be found in several locations, in the docs
Blender's Python Console
use the auto complete feature (ctrl+space) in the Blender python console after typing bpy.ops.mesh.primitive_

The arguments to the bpy.ops.* can be found doing auto completion too

Info Panel
You can see the history of most of the code which has been triggered in the UI, in the Info panel if you drag it down

"CTRL-C on a ToolTip" to copy the datapath or the Python function is a great TIP..works with SHIFT-CTRL-C on fields with values and checkboxes in all other windows

bpy.ops.mesh.primitive_plane_add(location=(x,y,z))

does the trick

will you please add more to this answer, to make it more useful for future viewers.


text:
Sidewalk and grassy dirt?
So, I think I actually "get" blender pretty well, I want to know from a workflow approach, how would I make a sidewalk, with lumpy ground underneath it. I want the sidewalk to look like it is pressing the dirt away, and the grass growing on my dirt should not be poking out through the "solid sidewalk" right now I have them as two separate objects, one named "sidewalk" the other "dirt" since they are both very different materials I assumed they need to be two different objects.
Generally the thing I'm looking for would also apply to how to make animal tracks in snow, tire tracks in sand, etc... if you guys could just point me in the right direction, I don't mind doing my research, I just don't know where to even start.  Oh, also, I can't shrinkwrap my sidewalk to the land, that would cause the sidewalk to be lumpy on top.
update
So, lol I just tried to apply the sidewalk as a shrinkwrap to the ground then I added the sidewalk to a vertex group, assign, selected only the top of the sidewalk vertexes and removed them from the group....That worked pretty well, now if I could get the particles to stop "coming through"
Here's what I want, the only comment I got seemed to focused on a very specific situation, as I said, this question applies to any situation where one surface should be "disturbed" by another.  Here are images like I am describing

The workflow I would use would depend upon the end use for the sidewalk and the dirt? My answer will be different if the end use is for a game, than if it for a stationary render. What is the surface of the sidewalk—concrete, bricks, or gravel? Again, my suggestion would depend upon the answer to this question. And what is the grass surface like? I'd take one approach for a well maintained lawn, another approach if the sidewalk and lawn are in a setting of urban decay, and still other techniques in other situations.

Please include an image of something similar to your artistic vision and a render or screen capture of what you have completed.  Your descriptions are difficult to read.  You wrote .... make a sidewalk, with lumpy grass under it. Do you mean sidewalk with grass on the sides?  I am trying to distinguish between [under] and [on the sides].

honestly you better go for one single mesh and use masks

ah! aha! @Yvain I could use a mask then invert copy the mesh to another object! that way I'd have both halves of the mold! good thinking I'll try that.

if you subdivide a plane, unwrap it, and paint a MASK as the one you can see here, you will be able to use it with a displace modifier, also use it to control the particles emission, and finally to split two materials with a mix slot.So that the object is one. Cheers.

YES! this is what I wanted! Now I can go google what all that means. Knowing what a hammer is is easy! it's knowing when to use it! that's what you provided thanks!

One question, could you let me know what's in those node groups?

The node going to the mix shader is an Add shader on which are connected a diffuse and a glossy material. The one going to the displace is a color mix using two different noise textures, the mask is connected to the factor slot. ;)


text:
What is the name of the add-on that adds "half and mirror mesh" options when pressing 'Q' key?
I have blender installed at two locations, on one pc, which is at work I have this amazing add-on that adds to the Q hot key options like, "half and mirror mesh" which I use all the time.  I'm at home and I really want to install that add-on here. but I don't know the name of it.
update
Here's a screenshot of the add-on

not with Q but ? http://blenderaddonlist.blogspot.fr/2014/07/addon-auto-mirror.html

So, I figured out the problem. At home I have quicktools version 0.7. The extra features I was missing were added in version 0.8.  The Github site with the add-on is only at version 0.7. I located version 0.8 hidden deep in the cgcookie site. I tried to install it locally it was failing, I didn't notice because the message was in the window header and flashed too quickly. So, to sum it up. I knew all along the right add-on, but it was failing to install and replace the previous version I had on my machine already.

And its name is?

Oh yeah oops.  Edited my answer. It was quicktools.


text:
Hair doesn't follow vertex group
Today I wanted to put some hair on my character. I used weight paint to make a vertex group. The hair particle system doesn't seem to follow the vertex group, though.

Can anybody help?
(I'm sorry for all the silly questions I've asked so far. But thanks for the answers!)
Edit: I've found the answer. Thanks though!

the one that you posted shows that you created a vertex group, the next step is to assign the hair particles in that vertex group.
particles -> vertex groups -> density -> and then scroll down to select the vertex group that you created


text:
How can I apply all Modifiers at once?
I have a scene that has hundreds of modifiers in it. When I try to render my scene, it takes FOREVER, so long that I cannot even render the scene! Help me please! How can I apply all of these modifiers all at once? I don't want to have to manually click "Apply" hundreds of times!


text:
How can I change the color of node names?
I'm using 2.69 and I'd like to make the node names much brighter, but I couldn't find a setting to do that. Did I miss it?

Thanks to Leon Cheung for this answer:
Theme -> Node Editor -> Theme Space Settings -> Text
Another alternative is:
Preferences -> Node Editor -> Node Backdrop

Also, oddly enough, if you change the alpha of Node Backdrop, it changes the alpha of the nodes, but not the alpha of the node names!

You should try Theme > Node Editor > Theme Space Settings > Text. Note that it also changes other text color on nodes, I think it's not that bad though. :)

Thank you Leon! That did work even better.
:)


text:
How can I position bones in a model easily and precisely?
I tried to position the hand bones of my rig / armature, but it was SO difficult to get all those little bones to align in 3D space accurately, even when I was using Quad View. After working on it for quite a while, I was SO frustrated I was ready to give up because I just couldn't get the bones positioned at all. Is there any way to do this quickly and easily?

Quick and Precise Bone Placement using Snap To
Positioning bones in a model can be quickly and easily achieved using two of Blender's Snap To commands:

Snap Selection to Cursor: this moves/snaps the selected object to the 3D Cursor (  )
SHIFTS -> Snap Selected to Cursor
Snap Cursor to Selected: this snaps the 3D Cursor to the selected object
SHIFTS -> Snap Cursor to Selected

For this method of bone placement, you will also want to enable two Interface preferences:

Zoom to Mouse Position: When enabled, the mouse pointer position becomes the focus point of zooming, instead of the 2D window center.
Rotate Around Selection: When enabled, the selected object becomes the rotation center of the viewport.

One other option that is very important is to make sure you can see your rig's bones even when they are inside the mesh. This is done by enabling X-Ray for your rig:

With these preferences enabled, you can now very easily examine your figure's mesh and begin to position the bones.
Positioning the Bones
There are 3 parts of a bone:

the Head (or Root)
the Body
the Tail (or Tip)

The key to this technique is to:

Find and select 2 vertices on opposite sides of your mesh's surface where you want to position the bone's tail:

NOTE: In order to see through the mesh, make sure "Limit Selection to Visible" is disabled:

Now, with those 2 points selected, use Snap 3D Cursor to Selected
SHIFTS -> Snap Cursor to Selected

This positions the 3D Cursor directly between the two selected vertices, exactly where we want to put the bone tail.
Now select the bone tail and snap it to the 3D Cursor:

Now we want to position the head of the bone at the tip of the finger. To do this, we select one vertex on the fingertip and snap the cursor to it:

Next, we snap the bone head to the 3D cursor:

The bone is now perfectly positioned.

You got head/tail in reverse


text:
Why does Blender 2.70 not stay in Orthographic view when rotating from, say, Front Ortho view?
I've just upgraded to 2.70 and now when I'm in Front Ortho view (or Back Ortho, Right Ortho, etc) and rotate out of it into User view, it switches out of Orthographic mode into Perspective. Blender 2.69 didn't do this? Why is it happening now in 2.70?

In blender 2.70 Auto Perspective is turned on be default in the user preferences. This will cause you to go from perspective to orthographic when changing from the User View a view like the side view. The same is true visa versa.
To change this behaviour you can edit the user preferences.

Open the user preferences, Ctrl Alt U
In the Interface tab disable Auto Perpective
To make this change permanent Save User Preferences

You are my hero. This has been a constant nuisance chipping away at my insanity ever since I upgraded to 2.70, and finally I decided to come here to ask this exact question only to find it was already answered!

For the people coming to this page from the future: In Blender 4.0, this option is in Navigation > Orbit & Pan > Auto > Perspective