question: The tripod camera things that land surveyors use, what are they for?
comment: I believe you're referring to a [theodolite]( URL_0 ). Surveyors use them to measure direction, distance, and elevation from a known point in order to accurately determine where something is in three-dimensional space.
passages: BULLET::::- Reconnaissance
  
  BULLET::::- Transportation projects in conjunction with ground surveys (roadway, bridge, highway)
  
  Aerial surveys use a measuring camera where the elements of its interior orientation are known, but with much larger focal length and film and specialized lenses.
  
  Section::::Aerial survey sensors.
   Section::::Channels and detectors.:High-Resolution Channel (HRC).
   Benchmark hunters also frequently carry a compass (to follow directions gleaned from the data sheet), a probe (like a long-bladed screwdriver) to search for buried marks, a trowel (or a small shovel) to uncover buried marks, a whisk broom (to clear away debris), and one or more tape measures of various lengths, used in taping out referenced distances found on the data sheets.
   For front-facing photography there are two sets of Piezo sensors that are linked as 1 - 3 and 2 - 4 in the road for Truvelo camera, both taking independent readings, if the two do not match (±2mph) the offence is discarded.
  
  Section::::Photographic evidence.
   Geophotography today takes numerous forms. At the most basic level, it can be accomplished using a film or digital Single-Lens Reflex (SLR) or "point-and-shoot" (compact) camera in the field or in the laboratory. In the field, special consideration is given to natural lighting of the object or feature being photographed. Scale is especially important in geophotography, and meter sticks, rock hammers, people, lens caps, coins, or other objects that are carried on-hand, are often placed in the frame to indicate the size of the feature being photographed. Images are generally cataloged automatically or manually with location information and grid reference (or latitude and longitude) data. These types of photographs are consistently used as visual aids in papers, field trip guides, reports, reviews, and posters. However, they are increasingly finding use as trackers of small-scale morphologic change, wherein photographs are repeatedly taken of particular features or places over time to show how the features or places are changing on a diurnal to annual time scale.
   Section::::ACS problems and fixes 2006–2009.
   BULLET::::- "Survey assistants" or "chainmen" are usually unskilled workers who help the surveyor. They place target reflectors, find old reference marks, and mark points on the ground. The term 'chainman' derives from past use of measuring chains. An assistant would move the far end of the chain under the surveyor's direction.
  
  BULLET::::- "Survey technicians" often operate survey instruments, run surveys in the field, do survey calculations, or draft plans. A technician usually has no legal authority and cannot certify his work. Not all technicians are qualified, but qualifications at the certificate or diploma level are available.
   Some modern, high-quality cameras also provide image stabilization, which compensates for vibration by moving inner workings of the camera, or electronically correcting the photograph.
   Although stations are no longer required for many surveying purposes, they remain useful to hikers as navigational aids.
  
  Section::::Stations worldwide.
  
  Section::::Stations worldwide.:Australia.
  
  A national geodetic survey and adjustment carried out in the early 1970s in Australia has left a legacy of trig stations, many consisting of a ground mark with a white quadripod supporting a black disc above the ground mark. Sometimes these trig stations are clearly visible for many kilometres and useful for hikers.
  
  Section::::Stations worldwide.:Japan.
  
  In Japan, there are five classes of :
  
  Section::::Stations worldwide.:South Africa.
   List of surveying instruments
  
  Instruments used in surveying include:
  
  BULLET::::- Cosmolabe
  
  BULLET::::- Dioptra
  
  BULLET::::- Theodolite
  
  BULLET::::- Half theodolite
  
  BULLET::::- Plain theodolite
  
  BULLET::::- Simple theodolite
  
  BULLET::::- Great theodolite
  
  BULLET::::- Non-transit theodolite
  
  BULLET::::- Transit theodolite
  
  BULLET::::- Seconds theodolite
  
  BULLET::::- Electronic theodolite
  
  BULLET::::- Mining theodolite
  
  BULLET::::- Suspension theodolite
  
  BULLET::::- Traveling theodolite
  
  BULLET::::- Pibal theodolite
  
  BULLET::::- Registering theodolite
  
  BULLET::::- Gyro-theodolite
  
  BULLET::::- Construction theodolite
  
  BULLET::::- Photo-theodolite
  
  BULLET::::- Robotic theodolite
  
  BULLET::::- Vernier theodolite
  
  BULLET::::- Tachymeter (surveying)
  
  BULLET::::- Graphometer
  
  BULLET::::- Universal instrument (surveying)
  
  BULLET::::- Transit (surveying)
  
  BULLET::::- Total station
  
  BULLET::::- Alidade
  
  BULLET::::- Alidade table
  
  BULLET::::- Plane table
  
  BULLET::::- Dumpy level
  
  BULLET::::- Tape (surveying)
  
  BULLET::::- Measuring tape
   Surveying instruments have characteristics that make them suitable for certain uses. Theodolites and levels are often used by constructors rather than surveyors in first world countries. The constructor can perform simple survey tasks using a relatively cheap instrument. Total stations are workhorses for many professional surveyors because they are versatile and reliable in all conditions. The productivity improvements from a GPS on large scale surveys makes them popular for major infrastructure or data gathering projects. One-person robotic-guided total stations allow surveyors to measure without extra workers to aim the telescope or record data. A fast but expensive way to measure large areas is with a helicopter, using a GPS to record the location of the helicopter and a laser scanner to measure the ground. To increase precision, surveyors place beacons on the ground (about apart). This method reaches precisions between 5–40 cm (depending on flight height).
   Modern top-of-the-line total stations no longer need a reflector or prism to return the light pulses used for distance measurements. They are fully robotic, and can even e-mail point data to a remote computer and connect to satellite positioning systems, such as Global Positioning System. Real Time Kinematic GPS systems have increased the speed of surveying, but they are still only horizontally accurate to about 20 mm and vertically to 30–40 mm.
   In the past, many surveyor's instruments were used on a Jacob's staff. These include:
  
  BULLET::::- Cross-head, cross-sight, surveyor's cross or cross
  
  BULLET::::- Graphometer
  
  BULLET::::- Circumferentor
  
  BULLET::::- Holland circle
  
  BULLET::::- Miner's dial
  
  BULLET::::- Optical square
  
  BULLET::::- Surveyor's sextant
  
  BULLET::::- Surveyor's target
  
  BULLET::::- Abney level
  
  Some devices, such as the modern optical targets for laser-based surveying, are still in common use on a Jacob's staff.
  
  Section::::In surveying.:In geology.
   BULLET::::- 1986–1988: Texas Instruments TI4100 portable Global Positioning System (GPS) geodetic receivers and Ferranti FILS3 helicopter and vehicle mounted Inertial Positioning System to replace TRANSIT satellite receivers
  
  BULLET::::- 1988–1990: established the baseline for a GPS controlled air camera and photogrammetric system to significantly reduce the requirement for ground survey to accurately control air photography for topographic mapping
   The optical plummet has either a bullseye or cross hair sight for positioning the instrument over a survey marker or ground control point. The older tribrachs required a plumb line to allow them to be positioned vertically over a point and took longer to set up.
  
  Some modern total stations have an integral laser plummet built in.
  
  Section::::Using a tribrach.
  
  The process is iterative between horizontal position and top plate level, because they are interactive. The following general process is followed:
  
  BULLET::::- The tribrach is attached to the tripod and placed over the marker.
   Section::::Surveying.
  
  A surveyor's tripod is a device used to support any one of a number of surveying instruments, such as theodolites, total stations, levels or transits.
  
  Section::::Surveying.:Usage.
  
  The tripod is placed in the location where it is needed. The surveyor will press down on the legs' platforms to securely anchor the legs in soil or to force the feet to a low position on uneven, pock-marked pavement. Leg lengths are adjusted to bring the tripod head to a convenient height and make it roughly level.
   Section::::Science instruments.:Television.
   Digital imaging technology was applied to rangefinder cameras for the first time in 2004, with the introduction of the Epson R-D1, the first ever digital rangefinder camera. The RD-1 was a collaboration between Epson and Cosina. The R-D1 and later R-D1s use Leica M-mount lenses, or earlier Leica screw mount lenses with an adapter.
  
  After the discontinuation of the R-D1, only Leica M digital rangefinders were in production until the introduction of two additional rangefinders in late 2018:
  
  BULLET::::- the Pixii Camera (A1112) from France-based firm Pixii SAS; and
   BULLET::::- "Surveying": To produce an accurate record of sites and buildings and to record accurately where the sites and buildings lie within the landscape. Surveyors use a range of equipment including tapes, plane tables, total stations, 3D scanners, GPS and GIS to produce illustrations including plans, sections and elevations as well as isometric and axonometric illustrations which are regularly used in building recording. Survey data will be gathered on acid free paper, polyvinyl permatrace and archive stable digital formats.
   The main surveying instruments in use around the world are the theodolite, measuring tape, total station, 3D scanners, GPS/GNSS, level and rod. Most instruments screw onto a tripod when in use. Tape measures are often used for measurement of smaller distances. 3D scanners and various forms of aerial imagery are also used.
   Section::::Science instruments.:Alpha-scattering surface analyzer.
   In the early part of the 20th century, Heinrich Wild produced theodolites that became popular with surveyors. His Wild T2, T3, and A1 instruments were made for many years, and he would go on to develop the DK1, DKM1, DM2, DKM2, and DKM3 for Kern Aarau company. With continuing refinements, instruments steadily evolved into the modern theodolite used by surveyors today.
  
  Section::::History.:Operation in surveying.
   Tripod (surveying)
  
  A surveyor's tripod is a device used to support any one of a number of surveying instruments, such as theodolites, total stations, levels or transits.
  
  Section::::History.
  
  The modern sturdy, but portable, tripod stand with three leg pairs hinged to a triangular metal head was invented and first manufactured for sale by Sir Francis Ronalds in the late 1820s in Croydon. He sold 140 of the stands in the decade 1830-40 and his design was soon imitated by others.
   In order to mitigate shaking associated with hand-holding a camera, landscape photography oftentimes requires a firm camera footing which affords the potential for sharper imagery. Tripods are specifically designed for stabilizing cameras and are widely regarded as essential equipment for landscape photography. However, any firm surface unaffected by vibration, wind or human contact may offer similar benefits. The use of a timer, remote control or cable release allows the shutter to be tripped without the introduction of vibration that might result from manually depressing the shutter button.
   Surveyors use ancillary equipment such as tripods and instrument stands; staves and beacons used for sighting purposes; PPE; vegetation clearing equipment; digging implements for finding survey markers buried over time; hammers for placements of markers in various surfaces and structures; and portable radios for communication over long lines of sight.
  
  Section::::Equipment.:Software.
  
  Land surveyors, construction professionals and civil engineers using total station, GPS, 3D scanners and other collector data use Land Surveying Software to increase efficiency, accuracy and productivity. Land Surveying Software is a staple of contemporary land surveying.
  
  Section::::Techniques.
  