Photogrammetry

# Photogrammetry

Discussion

Encyclopedia
Photogrammetry is the practice of determining the geometric properties of objects from photographic images. Photogrammetry is as old as modern photography
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...

and can be dated to the mid-nineteenth century.

In the simplest 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
Scale (map)
The scale of a map is defined as the ratio of a distance on the map to the corresponding distance on the ground.If the region of the map is small enough for the curvature of the Earth to be neglected, then the scale may be taken as a constant ratio over the whole map....

(s) of the image is known. This is done by multiplying the measured distance by 1/s.

A more sophisticated technique, called stereophotogrammetry, involves estimating the three-dimensional coordinates
Coordinate system
In geometry, a coordinate system is a system which uses one or more numbers, or coordinates, to uniquely determine the position of a point or other geometric element. The order of the coordinates is significant and they are sometimes identified by their position in an ordered tuple and sometimes by...

of points on an object. These are determined by measurements made in two or more photographic images taken from different positions (see stereoscopy
Stereoscopy
Stereoscopy refers to a technique for creating or enhancing the illusion of depth in an image by presenting two offset images separately to the left and right eye of the viewer. Both of these 2-D offset images are then combined in the brain to give the perception of 3-D depth...

). 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
Triangulation
In trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly...

) that determines the three-dimensional location of the point. More sophisticated algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

s can exploit other information about the scene that is known a priori
A priori and a posteriori (philosophy)
The terms a priori and a posteriori are used in philosophy to distinguish two types of knowledge, justifications or arguments...

, for example symmetries
Symmetry
Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...

, in some cases allowing reconstructions of 3D coordinates from only one camera position.

Photogrammetry is used in different fields, such as topographic map
Topographic map
A topographic map is a type of map characterized by large-scale detail and quantitative representation of relief, usually using contour lines in modern mapping, but historically using a variety of methods. Traditional definitions require a topographic map to show both natural and man-made features...

ping, architecture
Architecture
Architecture is both the process and product of planning, designing and construction. Architectural works, in the material form of buildings, are often perceived as cultural and political symbols and as works of art...

, engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...

, manufacturing
Manufacturing
Manufacturing is the use of machines, tools and labor to produce goods for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale...

, quality control
Quality control
Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...

, police
Police
The police is a personification of the state designated to put in practice the enforced law, protect property and reduce civil disorder in civilian matters. Their powers include the legitimized use of force...

investigation, and geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, as well as by archaeologists
Aerial archaeology
Aerial archaeology is the study of archaeological remains by examining them from altitude.The advantages of gaining a good aerial view of the ground had been long appreciated by archaeologists as a high viewpoint permits a better appreciation of fine details and their relationships within the wider...

to quickly produce plans of large or complex sites and by meteorologists as a way to determine the actual wind speed of a tornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...

where objective weather data cannot be obtained. It is also used to combine live action
Live action
In filmmaking, video production, and other media, the term live action refers to cinematography, videography not produced using animation...

with computer-generated imagery
Computer-generated imagery
Computer-generated imagery is the application of the field of computer graphics or, more specifically, 3D computer graphics to special effects in art, video games, films, television programs, commercials, simulators and simulation generally, and printed media...

in movie post-production
Post-production
Post-production is part of filmmaking and the video production process. It occurs in the making of motion pictures, television programs, radio programs, advertising, audio recordings, photography, and digital art...

; Fight Club
Fight Club (film)
Fight Club is a 1999 American film based on the 1996 novel of the same name by Chuck Palahniuk. The film was directed by David Fincher and stars Edward Norton, Brad Pitt and Helena Bonham Carter. Norton plays the unnamed protagonist, an "everyman" who is discontented with his white-collar job...

is a good example of the use of photogrammetry in film (details are given in the DVD extras).

Algorithms for photogrammetry typically express the problem as that of minimizing the sum of the squares of a set of errors. This minimization is known as bundle adjustment
Given a set of images depicting a number of 3D points from different viewpoints, bundle adjustment can be defined as the problem of simultaneously refining the 3D coordinates describing the scene geometry as well as the parameters of the relative motion and the optical characteristics of the camera...

and is often performed using the Levenberg–Marquardt algorithm.

## Photogrammetric methods

Photogrammetry uses methods from many disciplines, including optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...

and projective geometry
Projective geometry
In mathematics, projective geometry is the study of geometric properties that are invariant under projective transformations. This means that, compared to elementary geometry, projective geometry has a different setting, projective space, and a selective set of basic geometric concepts...

. The data model on the right shows what type of information can go into and come out of photogrammetric methods.

The 3D co-ordinates define the locations of object points in the 3D space. The image co-ordinates 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.

Photogrammetry has been defined by the American Society for Photogrammetry and Remote Sensing
American Society for Photogrammetry and Remote Sensing
The American Society for Photogrammetry and Remote Sensing, or ASPRS is the United States member organization of the International Society for Photogrammetry and Remote Sensing. Founded in 1934, the society is a scientific association serving over 7,000 professional members around the world...

(ASPRS) as the art, science, and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring and interpreting photographic images and patterns of recorded radiant electromagnetic energy and other phenomena.

## Integration

Photogrammetric data with dense range data from scanners complement each other. Photogrammetry is more accurate in the x and y direction while range data is generally more accurate in the z direction. This range data can be supplied by techniques like LiDAR
LIDAR
LIDAR is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser...

, 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"). 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
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

-based approaches, although these techniques may still be useful in deriving elevation models from old aerial photographs or satellite images.

## Applications

This method is commonly employed in collision engineering, especially with automobiles. When litigation for accidents 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 crime 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).

## Current Suite of Software

Standalone / Plugin Specialisation Automatic modelling Scalability Data source Inception Vendor / creator Guide price Link
PhotoSculpt Standalone 100% Yes No, 2 images only Images - Hippolyte Mounier \$99 http://www.photosculpt.net/
PhotoModeler Standalone 100% Yes Yes, multiple images Images 1994 Eos Systems \$1145 http://www.photomodeler.com
ImageModeler Standalone 100% No Yes, multiple images Images 2009 Autodesk Subscription benefit http://usa.autodesk.com/adsk/servlet/pc/index?id=11390028&siteID=123112
3D VIA Standalone 100% No Yes Images Example Example Example http://www.3dvia.com/
PhotoSketch - - - - - - Brainstorm Technology LLC \$350 http://www.brainstormllc.com/
3D pup-up Standalone 100% No Single image Image 2005 Carnegie Mellon University non commercial http://www.cs.uiuc.edu/homes/dhoiem/projects/popup/index.html
Yodel Standalone 100% Limited Yes, multiple images Images 2011 Lidar Pacific Corporation \$499 http://www.yodel3d.com
VideoTrace Tethered Beta 100% No Yes, multiple images Images/Video 2011 Australian Center for Visual Technology (AVCT),PunchCard Beta Tester Only http://punchcard.com.au/wordpress/
123D Catch (Beta) Standalone 100% Yes Yes, multiple images Images/Video 2011 Autodesk Free download http://www.123dapp.com/catch
Hypr3D Standalone 100% Yes Yes, multiple images Images/Video 2010 Viztu Technologies Free, web-based https://www.hypr3d.com/
ELCOVISION 10 Standalone/Plugin 100% Yes Yes, multiple images Images 1986 PMS AG / Leica Geosystems 2000 http://www.elcovision.com/
PhotoScan Standalone/Plugin 100% Semi-automatic Yes, multiple images Images 2010 Ocali, Inc. \$999 http://www.Tgi3D.com/

• 3D data acquisition and object reconstruction
3D data acquisition and object reconstruction
3D data acquisition and reconstruction is the generation of three dimensional or spatiotemporal models from sensor data. The techniques and theories, generally speaking, work with most or all sensor types including optical, acoustic, laser scanning, radar, thermal, seismic.-Acquisition:Acquisition...

• Aerial survey
Aerial survey
Aerial survey is a geomatics method of collecting information by using aerial photography, LiDAR or from remote sensing imagery using other bands of the electromagnetic spectrum, such as infrared, gamma, or ultraviolet. It can also refer to the chart or map made by analysing a region from the air...

• Computer vision
Computer vision
Computer vision is a field that includes methods for acquiring, processing, analysing, and understanding images and, in general, high-dimensional data from the real world in order to produce numerical or symbolic information, e.g., in the forms of decisions...

• Edouard Deville
Edouard Deville
Édouard-Gaston Daniel Deville was the first to perfect a practical method of photogrammetry, the making of maps based on photography. He was the Surveyor General of Canada and Canada's Director General for the Bureau of Surveys...

• ERDAS IMAGINE
ERDAS IMAGINE
ERDAS IMAGINE is a remote sensing application with raster graphics editor capabilities designed by ERDAS for geospatial applications. The latest version is 2010, version 10.1. ERDAS IMAGINE is aimed primarily at geospatial raster data processing and allows the user to prepare, display and enhance...

• Geofoto
Geofoto
Geofoto is a Croatian company with 260 employees headquartered in Zagreb, Croatia with subsidiaries in Norway, Macedonia, Slovenia, Bolivia, Argentina, United Arab Emirates, Czech Republic and United Kingdom. Its main fields are Geomatics activities such as photogrammetry and geographic information...

• Geoinformatics
Geoinformatics
Geoinformatics is the science and the technology which develops and uses information science infrastructure to address the problems of geography, geosciences and related branches of engineering.-Overview:...

• Geomatics engineering
Geomatics engineering
Geomatics Engineering, Geomatic Engineering, or Geospatial Engineering is a rapidly developing discipline that focuses on spatial information . The location is the primary factor used to integrate a very wide range of data for viewing and analysis...

• Leica Photogrammetry Suite
Leica Photogrammetry Suite
Leica Photogrammetry Suite is a software application for performing photogrammetric operations on imagery and extracting information from imagery...

• Mobile Mapping
Mobile Mapping
Mobile mapping is the process of collecting geospatial data from a mobile vehicle, typically fitted with a range of photographic, radar, laser, LiDAR or any number of remote sensing systems. Such systems are composed of an integrated array of time synchronised navigation sensors and imaging sensors...

• Periscope
Periscope
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle....

• Photomapping
Photomapping
Photomapping involves the process of drawing a map from a photographic base. “In all likelihood, computer map making, including analogue processing, will have replaced manual map making for well over 90 per cent of all maps".-Principles and Definitions:...

• PhotoModeler
PhotoModeler
PhotoModeler is a software application that performs image-based modeling and close range photogrammetry – producing 3D models and measurements from photography....

• Rangefinder
Rangefinder
A rangefinder is a device that measures distance from the observer to a target, for the purposes of surveying, determining focus in photography, or accurately aiming a weapon. Some devices use active methods to measure ; others measure distance using trigonometry...

• SOCET SET
SOCET SET
SOCET SET is a software application that performs functions related to photogrammetry. It is developed and published by BAE Systems. SOCET SET was the first commercial digital photogrammetry software program...

• Stereoplotter
Stereoplotter
A stereoplotter uses stereo photographs to determine elevations. It has been the primary method to plot contour lines on topographic maps since the 1930’s...

• Surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

• TopoFlight
TopoFlight
TopoFlight is a three-dimensional flight planning software that was originally conceived by a team of experts in the mapping industry, in use since 2003...

• Videogrammetry
Videogrammetry
Videogrammetry is a measurement technology in which the three-dimensional coordinates of points on an object are determined by measurements made in two or more video images taken from different angles. Images can be obtained from two cameras which simultaneously view the object or from successive...