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Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena. The term photogrammetry was coined by the Prussian architect Albrecht Meydenbauer, which appeared in his 1867 article "Die Photometrographie." There are many variants of photogrammetry. One example is the extraction of three-dimensional measurements from two-dimensional data (i.e. images); for example, the distance between two points that lie on a plane parallel to the photographic image plane can be determined by measuring their distance on the image, if the scale of the image is known. Another is the extraction of accurate
color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are assoc ...
ranges and values representing such quantities as
albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refl ...
, specular reflection, metallicity, or
ambient occlusion In 3D computer graphics, modeling, and animation, ambient occlusion is a shading and rendering technique used to calculate how exposed each point in a scene is to ambient lighting. For example, the interior of a tube is typically more occluded ...
from photographs of materials for the purposes of
physically based rendering Physically based rendering (PBR) is a computer graphics approach that seeks to render images in a way that models the flow of light in the real world. Many PBR pipelines aim to achieve photorealism. Feasible and quick approximations of the b ...
. Close-range photogrammetry refers to the collection of photography from a lesser distance than traditional aerial (or orbital) photogrammetry. Photogrammetric analysis may be applied to one photograph, or may use
high-speed photography High-speed photography is the science of taking pictures of very fast phenomena. In 1948, the Society of Motion Picture and Television Engineers (SMPTE) defined high-speed photography as any set of photographs captured by a camera capable of 69 ...
and remote sensing to detect, measure and record complex 2D and 3D motion fields by feeding measurements and
imagery analysis Image analysis or imagery analysis is the extraction of meaningful information from images; mainly from digital images by means of digital image processing techniques. Image analysis tasks can be as simple as reading bar coded tags or as sophist ...
into
computational models A computational model uses computer programs to simulate and study complex systems using an algorithmic or mechanistic approach and is widely used in a diverse range of fields spanning from physics, chemistry and biology to economics, psychology, ...
in an attempt to successively estimate, with increasing accuracy, the actual, 3D relative motions. From its beginning with the stereoplotters used to plot
contour line A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional grap ...
s on
topographic map In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but histori ...
s, it now has a very wide range of uses such as
sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...
,
radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...
, and lidar.


Methods

Photogrammetry uses methods from many disciplines, including
optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...
and
projective geometry In mathematics, projective geometry is the study of geometric properties that are invariant with respect to projective transformations. This means that, compared to elementary Euclidean geometry, projective geometry has a different setting, ...
. Digital image capturing and photogrammetric processing includes several well defined stages, which allow the generation of 2D or 3D digital models of the object as an end product. The data model on the right shows what type of information can go into and come out of photogrammetric methods. The ''3D coordinates'' define the locations of object points in the
3D space Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called ''parameters'') are required to determine the position of an element (i.e., point). This is the informa ...
. The ''image coordinates'' define the locations of the object points' images on the film or an electronic imaging device. The '' exterior orientation'' of a camera defines its location in space and its view direction. The '' inner orientation'' defines the geometric parameters of the imaging process. This is primarily the focal length of the lens, but can also include the description of lens distortions. Further ''additional observations'' play an important role: With ''scale bars'', basically a known distance of two points in space, or known ''fix points'', the connection to the basic measuring units is created. Each of the four main variables can be an ''input'' or an ''output'' of a photogrammetric method. Algorithms for photogrammetry typically attempt to minimize the sum of the squares of errors over the coordinates and relative displacements of the reference points. This minimization is known as bundle adjustment and is often performed using the
Levenberg–Marquardt algorithm In mathematics and computing, the Levenberg–Marquardt algorithm (LMA or just LM), also known as the damped least-squares (DLS) method, is used to solve non-linear least squares problems. These minimization problems arise especially in least sq ...
.


Stereophotogrammetry

A special case, called stereophotogrammetry, involves estimating the three-dimensional coordinates of points on an object employing measurements made in two or more photographic images taken from different positions (see stereoscopy). Common points are identified on each image. A line of sight (or ray) can be constructed from the camera location to the point on the object. It is the intersection of these rays ( triangulation) that determines the three-dimensional location of the point. More sophisticated
algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s can exploit other information about the scene that is known '' a priori'', for example symmetries, in some cases allowing reconstructions of 3D coordinates from only one camera position. Stereophotogrammetry is emerging as a robust non-contacting measurement technique to determine dynamic characteristics and mode shapes of non-rotating and rotating structures. The collection of images for the purpose of creating photogrammetric models can be called more properly, polyoscopy, after Pierre Seguin


Integration

Photogrammetric data can be complemented with range data from other techniques. Photogrammetry is more accurate in the x and y direction while range data are generally more accurate in the z direction . This range data can be supplied by techniques like LiDAR, laser scanners (using time of flight, triangulation or interferometry), white-light digitizers and any other technique that scans an area and returns x, y, z coordinates for multiple discrete points (commonly called "
point clouds Point or points may refer to: Places * Point, Lewis, a peninsula in the Outer Hebrides, Scotland * Point, Texas, a city in Rains County, Texas, United States * Point, the NE tip and a ferry terminal of Lismore, Inner Hebrides, Scotland * Point ...
"). Photos can clearly define the edges of buildings when the point cloud footprint can not. It is beneficial to incorporate the advantages of both systems and integrate them to create a better product. A 3D visualization can be created by georeferencing the aerial photos and LiDAR data in the same reference frame, orthorectifying the aerial photos, and then draping the orthorectified images on top of the LiDAR grid. It is also possible to create digital terrain models and thus 3D visualisations using pairs (or multiples) of aerial photographs or satellite (e.g. SPOT satellite imagery). Techniques such as adaptive least squares stereo matching are then used to produce a dense array of correspondences which are transformed through a camera model to produce a dense array of x, y, z data which can be used to produce digital terrain model and orthoimage products. Systems which use these techniques, e.g. the ITG system, were developed in the 1980s and 1990s but have since been supplanted by LiDAR and radar-based approaches, although these techniques may still be useful in deriving elevation models from old aerial photographs or satellite images.


Applications

Photogrammetry is used in fields such as
topographic map In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but histori ...
ping,
architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...
,
engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more speciali ...
,
manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to ...
, quality control,
police The police are a constituted body of persons empowered by a state, with the aim to enforce the law, to ensure the safety, health and possessions of citizens, and to prevent crime and civil disorder. Their lawful powers include arrest and th ...
investigation, cultural heritage, and
geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...
. Archaeologists use it to quickly produce plans of large or complex sites, and
meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while t ...
s use it to determine the wind speed of tornadoes when objective weather data cannot be obtained. It is also used to combine live action with computer-generated imagery in movies post-production; ''
The Matrix ''The Matrix'' is a 1999 science fiction action film written and directed by the Wachowskis. It is the first installment in ''The Matrix'' film series, starring Keanu Reeves, Laurence Fishburne, Carrie-Anne Moss, Hugo Weaving, and Joe Pantolia ...
'' is a good example of the use of photogrammetry in film (details are given in the DVD extras). Photogrammetry was used extensively to create photorealistic environmental assets for video games including '' The Vanishing of Ethan Carter'' as well as EA DICE's '' Star Wars Battlefront''. The main character of the game '' Hellblade: Senua's Sacrifice'' was derived from photogrammetric motion-capture models taken of actress Melina Juergens. Photogrammetry is also commonly employed in collision engineering, especially with automobiles. When litigation for a collision occurs and engineers need to determine the exact deformation present in the vehicle, it is common for several years to have passed and the only evidence that remains is crash scene photographs taken by the police. Photogrammetry is used to determine how much the car in question was deformed, which relates to the amount of energy required to produce that deformation. The energy can then be used to determine important information about the crash (such as the velocity at time of impact).


Mapping

Photomapping is the process of making a map with "cartographic enhancements"Petrie (1977: 50) that have been drawn from a
photomosaic In the field of photographic imaging, a photographic mosaic, also known under the term Photomosaic, is a picture (usually a photograph) that has been divided into (usually equal sized) tiled sections, each of which is replaced with another phot ...
Petrie (1977: 49) that is "a composite photographic image of the ground," or more precisely, as a controlled photomosaic where "individual photographs are rectified for tilt and brought to a common scale (at least at certain control points)." Rectification of imagery is generally achieved by "fitting the projected images of each photograph to a set of four control points whose positions have been derived from an existing map or from ground measurements. When these rectified, scaled photographs are positioned on a grid of control points, a good correspondence can be achieved between them through skillful trimming and fitting and the use of the areas around the principal point where the relief displacements (which cannot be removed) are at a minimum."Petrie (1977: 50) "It is quite reasonable to conclude that some form of photomap will become the standard general map of the future."Robinson et al. (1977:10) They go on to suggest that, "photomapping would appear to be the only way to take reasonable advantage" of future data sources like high altitude aircraft and satellite imagery. The highest resolution aerial photomaps on GoogleEarth are approximately spatial resolution images. The highest resolution photomap of ortho images was made in Hungary in 2012 with a spatial resolution.


Archaeology

Demonstrating the link between orthophotomapping and
archaeology Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landsca ...
,Estes et al. (1977) historic airphotos photos were used to aid in developing a reconstruction of the Ventura mission that guided excavations of the structure's walls. Overhead photography has been widely applied for mapping surface remains and excavation exposures at archaeological sites. Suggested platforms for capturing these photographs has included: War Balloons from World War I;Capper (1907) rubber meteorological balloons;Guy (1932)
kites A kite is a tethered heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create lift and drag forces. A kite consists of wings, tethers and anchors. Kites often have a bridle and tail to guide the face ...
;Guy (1932)Bascom (1941) wooden platforms, metal frameworks, constructed over an excavation exposure;Guy (1932) ladders both alone and held together with poles or planks; three legged ladders; single and multi-section poles;Schwartz (1964)Wiltshire (1967) bipods;Kriegler (1928)Hampl (1957)Whittlesey (1966)Fant and Loy (1972) tripods;Straffin (1971) tetrapods,Simpson and Cooke (1967)Hume (1969) and aerial bucket trucks ("cherry pickers").Sterud and Pratt (1975) Handheld, near-nadir, overhead digital photographs have been used with geographic information systems ( GIS) to record excavation exposures.Craig (2000)Craig (2002)Craig and Aldenderfer (2003)Craig (2005)Craig et al. (2006) Photogrammetry is increasingly being used in
maritime archaeology Maritime archaeology (also known as marine archaeology) is a discipline within archaeology as a whole that specifically studies human interaction with the sea, lakes and rivers through the study of associated physical remains, be they vessels, s ...
because of the relative ease of mapping sites compared to traditional methods, allowing the creation of 3D maps which can be rendered in virtual reality.


3D modeling

A somewhat similar application is the scanning of objects to automatically make 3D models of them. Since photogrammetry relies on images, there are physical limitations when those images are of an object that has dark, shiny or clear surfaces. In those cases, the produced model often still contains gaps, so additional cleanup with software like
MeshLab MeshLab is a 3D mesh processing software system that is oriented to the management and processing of unstructured large meshes and provides a set of tools for editing, cleaning, healing, inspecting, rendering, and converting these kinds of meshes ...
, netfabb or MeshMixer is often still necessary. Alternatively, spray painting such objects with matte finish can remove any transparent or shiny qualities. Google Earth uses photogrammetry to create 3D imagery. There is also a project called Rekrei that uses photogrammetry to make 3D models of lost/stolen/broken artifacts that are then posted online.


Software

There exist many software packages for photogrammetry; see
comparison of photogrammetry software Photogrammetry is the technique to extract geometric information from two-dimensional images or video. Comparison of notable packages See also *MicMac (software) *PCI Geomatica *Bundle adjustment#Software, Bundle adjustment software *Str ...
.
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, where its wild ancestor, ' ...
introduced a photogrammetry API called Object Capture for macOS Monterey at the 2021 Apple Worldwide Developers Conference. In order to use the software, however, "you need an iPhone or iPad with a dual-lens rear camera (and preferably a LiDAR scanner, although not required) to capture depth data," in addition to a MacBook running macOS Monterey.


See also


References


Sources

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External links


History of Photogrammetry

Photogrammetry overview on the Cultural Heritage Imaging web site
{{Authority control Articles containing video clips