Showing papers on "Photogrammetry published in 1993"

Particle tracking velocimetry in three-dimensional flows

Abstract: Particle Tracking Velocimetry (PTV) is a well-known technique for the determination of velocity vectors within an observation volume. However, for a long time it has rarely been applied because of the intensive effort necessary to measure coordinates of a large number of flow marker particles in many images. With today's imaging hardware in combination with the methods of digital image processing and digital photogrammetry, however, new possibilities have arisen for the design of completely automatic PTV systems. A powerful 3D PTV has been developed in a cooperation of the Institute of Geodesy and Photogrammetry with the Institute of Hydromechanics and Water Resources Management at the Swiss Federal Institute of Technology. In this paper hardware components for 3D PTV systems wil be discussed, and a strict mathematical model of photogrammetric 3D coordinate determination, taking into account the different refractive indices in the optical path, will be presented. The system described is capable of determining coordinate sets of some 1000 particles in a flow field at a time resolution of 25 datasets per second and almost arbitrary sequence length completely automatically after an initialization by an operator. The strict mathematical modelling of the measurement geometry, together with a thorough calibration of the system provide for a coordinate accuracy of typically 0.06 mm in X, Y and 0.18 mm in Z (depth coordinate) in a volume of 200 × 160 × 50 mm3.

Advanced terrain mapping system

Abstract: A tractor and trailer together with a post-processing system that uses GPS satellites together with a dead reckoning system and associated cameras and sensors to determine the exact location of the system, translating this location information onto several photogrammetric mapping collectors for the purposes of developing an orthographic database image that can be correlated with other onboard sensors for determining the precise location of terrain features. The main sensor platform comprises a GPS receiver together with a plurality of visual sensors and a dead reckoning system mounted on a trailer. The GPS data and the dead reckoning data are brought together in a navigation system to provide precise location of the system. The camera system on board the trailer of the system comprises a series of cameras for recording images of the terrain as the trailer proceeds over the terrain of interest. During data collection, digital imagery is transmitted from each camera and received by an on-board computer. The collection of image data is triggered by the movement of the vehicle a certain distance along the ground. Simultaneously with the collection of the digital image data, the on-board GPS system and dead reckoning system are queried for geographical reference. A dataframe is then created and stored for each form of imagery from each camera. During post processing, an operator can extract highly accurate geographic coordinates from a combination of photogrammetric techniques using the stored images and geographic data. The system outputs hardcopy engineering plots and softcopy digital vector files.

Developments in photogrammetry; the geomorphological potential

Abstract: Current emphasis in geomorphology recognizes the need for the accurate representation of topographic form, reflected in the growth of digital terrain and elevation modelling. A key requirement of such strategies is the efficient acquisition of information in an appropriate form and at an appropriate resolution to the landform under consideration. The traditional use of photographs in geomorphology has been for interpretation, but developments in photogrammetry may allow the full advantages of the photograph as a means of acquiring and storing quantitative information to be used. The photograph can provide information on all areas visible on a photograph; the information is acquired retrodictively; the photograph preserves the spatial relationship of morphological units; the collection of photographs requires minimal landform contact; the photograph records extra explanatory information; and photographs can be obtained at an appropriate temporal resolution to the landform under investigation. However, opti...

Multicamera vision-based approach to flexible feature measurement for inspection and reverse engineering

Abstract: The vision-based coordinate measurement system, developed at the National Research Council Canada, is a multicamera passive system that combines the principles of stereo vision, photogrammetry, knowledge-based techniques, and an object-oriented design methodology to provide precise coordinate and dimension measurements of parts for applications such as dimensional inspection, positioning and tracking of objects, and reverse engineering. For a vision system to be considered for such applications, its performance and design parameters must be well understood. A description of the system, the techniques employed for calibration, a performance evaluation procedure, an accuracy analysis, and test results are presented.

DEM matching and detection of deformation in close-range photogrammetry without control

Abstract: A method for matching pairs of digital elevation models (DEMs), based on surface shape and without control points, has been evaluated in close-range photogrammetry. Results presented for 30 DEM pairs of the human body trunk and of varying relief indicate that the influence of orientation errors has been effectively removed from the transformed models. The final RMS differences in relief are close to the RMS errors of the elevations themselves. Introduction of gross error detection techniques, such as «data-snooping,» simultaneously allows orientation based on similar model regions and localization of deformations. The magnitude of the latter is adequately estimated using the weight cofactor matrix of residuals

Mathematical models of the accuracy of digital terrain model surfaces linearly constructed from square gridded data

Abstract: This paper presents two mathematical models of the accuracy of digital terrain model (DTM) surfaces which have been linearly constructed from square gridded data, respectively with and without additional feature specific data. In these models, the accuracy of DTM surfaces is expressed as a function of a few parameters, such as slope angle, grid interval or the accuracy of raw data, which are familiar to practitioners in photogrammetry and other mapping related disciplines. These models are in a form similar to the conventional formulae for contour map accuracy and they are compared with experimental test results.

Relationship between photogrammmetry and computer vision

Abstract: The relationship between photogrammetry and computer vision is examined This paper reviews the central issues for both computer vision and photogrammetry and the shared goals as well as distinct approaches are identified Interaction in the past has been limited by both differences in terminology and in the basic philosophy concerning the manipulation of projection equations The application goals and mathematical techniques of both fields have considerable overlap and so improved dialogue is essential

Reservoir Analog Studies Using Multimodel Photogrammetry: A New Tool for the Petroleum Industry

Abstract: An advanced photogrammetric method called multimodel stereo restitution is a potential new tool for the petroleum industry when outcrop investigations are necessary, such as in reservoir analog studies. The method is based on very simple field photography techniques, allowing the geologist to use his own standard small-frame camera (e.g., 24 × 36 or 60 × 60 mm formats). It can be applied to geological studies of virtually any scale, and outcrop mapping is significantly improved in detail, accuracy, and volume. The method is especially useful when investigating poorly accessible exposures on steep mountain faces and canyon walls. The use of multimodel photogrammetry is illustrated by a study of Upper Cretaceous deltaic sediments from the Atane Formation of West Greenland. Detailed vertical cross sections of all outcrops in the area are measured, and in addition, horizontal maps of individual sand bodies are compiled. On this basis, data such as width/thickness ratios, sinuosity, and the shapes of sand bodies and paleochannels crucial in reservoir analog studies are quantified and collected. Further potential applications of the method in petroleum explorations are discussed. True-scale mapping of lithologies in large continuous exposures can be used in understanding basin evolution and in seismic modeling. Close-range applications can be used when modeling fault geometries, and in studies of individual bed forms, clay laminae, cemented horizons, and diagenetic fronts.

GPS control for 1:50,000-scale topographic mapping from satellite images

Abstract: Ortho-images from digital SPOT satellite data were generated to test their application in production and updating of 1:50,000-scale Canadian National Topographic Maps. The orbital parameters were modeled with Ground Control Points (GCP), and the transformation between image and geographic coordinates was defined. Successful production and update of digital map files, or GIS feature extraction from base images, requires knowledge of the total error budget in the ortho-image process. The errors were found to include the GCP geographic position error, the pointing error for GCPs in image coordinates, DEM error, and transformation and resampling errors.

Photogrammetric calibration for improved three-dimensional particle-tracking velocimetry (3D PTV)

Abstract: Photogrammetry, the measurement of three-dimensional object coordinates from stereo photographicimages, is an essential element of 3-D PTV. Ray tracing is the method that has been used traditionally,however it requires accurate knowledge of image distance, camera locations relative to the object field, andthe size, shape, and refractive index of intervening elements such as apparatus windows. These parametersneed not be known if one uses an optical transform and in situ photogrammetric calibration. The useof this technique significantly reduces the computational time required for 3-D PTV and increases theaccuracy of the measured velocity fields.This technique has been integrated with two others we have recently developed: one is 2-D particletracking using the concept of "path coherence", and the other is stereo matching based on 2-D "particletracks" rather than the particles themselves. In combination, these techniques make 3-D PTV a powerfuland effective tool for advanced research in fluid dynamics and for product development where fluid motionplays a major role in the success of the design, e.g. piston engines.

Suitability of the Pulnix TM6CN CCD camera for photogrammetric measurement

Abstract: The Pulnix TM6CN CCD camera appears to be a suitable choice for many close range photogrammetric applications where the cost of the final system is a factor. The reasons for this are: its small size, low power consumption, pixel clock output, variable electronic shutter, and relatively high resolution. However, to have any confidence in such a camera a thorough examination is required to assess its characteristics. In this paper an investigation of three of these cameras is described, and their suitability for close range photogrammetry evaluated. The main factors assessed are system component influences, warm-up effects, line jitter, principal point location and lens calibration. The influence of the frame-store on the use of the camera is also estimated and where possible excluded. Results of using these cameras for close range measurement are given and analyzed. While many users will have or prefer to buy other cameras, the evaluation of this particular camera should give an understanding of the important features of such image sensors, their use in photogrammetric measuring systems and the processes of evaluating their physical properties.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A resume of some industrial applications of photogrammetry

Abstract: Photogrammetry displays many attributes which make it an ideal tool for precise industrial measurement. Modern automated photogrammetric systems are fast, accurate, reliable, flexible and economical in comparison to traditional as well as some modern three-dimensional coordinate measuring techniques. The benefits of industrial photogrammetry have attracted growing recognition over the past decade, to the point where the method is now a widely used measurement tool, especially in the aerospace, aircraft manufacturing, microwave antenna and shipbuilding industries. In this paper the role of close-range photogrammetry in industry is discussed. Characteristics of the technique are reviewed, systems aspects are touched upon, and four diverse applications are summarized.

State-of-the-art digital photogrammetric workstations for topographic applications

Abstract: Digital Photogrammetric Workstations (DPWS) have become a major focus of research within the photogrammetric community in the last year. This paper presents the state-of-the-art of DPWS. A DPWS is the main component of a Digital Photogrammetric Systems (DPS). A DPS is defined as hardware and software for deriving input data for Geographic Information Systems (GIS) as well as for Computer Aided Design (CAD) systems and other photogrammetric products from digital imagery using manual and automatic techniques. Besides the DPWS itself a DPS also includes A/D and D/A convertors for the imagery (digital cameras, film scanners, output devices for producing film and paper hardcopies). First design issues of a DPWS are addressed. Then, the question of automation versus interaction is discussed, and it is pointed out, where automation is possible in the chain of processing digital imagery. Subsequently a classification of the different kinds of DPWS according to their products is given. Then first experiences and results obtained by civilian mapping organizations involved in digital photogrammetry and using DPWS are described. Finally requirements for a broader use in practice and trends for further development in digital photogrammetry and in DPS are pointed out.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Photogrammetry and kinematic GPS: results of a high accuracy test

Abstract: Aerial triangulation with kinematic GPS support has become an important issue during the past few years. This article reports on the results of a research project that was aimed at demonstrating the valuable contributions that kinematic GPS can make to photogrammetric bundle triangulation. An accuracy of μ xy = 5 cm in planimetry and μ z = 8 cm in height was obtained for ground check points from an image scale of 1:10,000 with only four control points in the block corners. This accuracy corresponds to the values which can be obtained with a large number of ground control points (bridging distance i = 2b) but without integration of kinematic GPS data

Evaluation of a soft-copy photogrammetry system for tree-plot measurements

Abstract: This article describes and evaluates the application of a soft-copy photogrammetry system to large-scale forest inventories. A specially designed software, developed by the authors, has been investigated in terms of accuracy and general operability. Tests based on 1:1100 color aerial photographs, taken with a 10-m cross-boom system and digitized at resolutions of 300, 450, and 600 dots per inch, confirmed the expected tree-height accuracies of 48, 32, and 24 cm, respectively. This indicates that a photographic scale of 1:800 and a scanning resolution of 800 dots per inch could produce a tree-height precision of the order of 10 cm. The tests have shown that model orientation takes about 15 min; for a tree plot of 24 trees, measurements (height and crown diameter) and observations (species and condition) also take about 15 min. As the important problem of positioning a helicopter over a tree plot has now been solved using global positioning system receivers, the results and information presented in this pap...

Accuracy of Three-Dimensional Photogrammetry as Established by Controlled Field Tests

Abstract: Photogrammetry is the science of obtaining spatial information from photographs given a set of key reference points. Vehicular accident reconstruction frequently requires using the photogrammetric process to obtain dimensions of such items as skid mark length, vehicle rest positions, or depth of vehicle crush. This paper briefly describes the generalized three-dimensional photogrammetric process. Findings show the accuracy of this process when applied to simulated reconstruction situations involving skid marks and vehicle crush. Three sets of photographs of simulated skid marks and one of vehicle crush were analyzed photogrammetrically, and results were compared to a blind set of survey data. The comparison between the survey data and photogrammetry calculations are presented in graphical form.

Calibration of video cameras for scoliosis mapping

Abstract: Basic surveying and photogrammetric tools of the surveyor can be used for small object mapping as well as for terrain mapping. Monitoring progression and evaluating treatment of spinal deformity is...

Photogrammetry and projective geometry: an historical survey

Abstract: General Jean-Victor Poncelet published his treatise on projective geometry in 1822. This was the start of an enormous development in geometry in the 19th century. During this period geometry in the plane and in 3-dimensional space was studied in particular detail. The development culminated in the publishing of the Encyclopedia of Mathematics, which appeared in irregular installments from 1900 to 1934. Photogrammetry—the use of photographic images for surveying, mapping and reconnaissance—began in the second half of the 19th century. By the 1890's substantial theoretical contributions were made by Sebastian Finsterwalder. Finsterwalder reported on his foundational work in a keynote address to the German Mathematical Society in 1897; he also contributed an article on photogrammetry to the Encyclopedia of Mathematics. Among other things Finsterwalder observed that Rudolf Sturm's analysis of the "homography problem" (1869) can be used to solve the problem of 3D-reconstruction using point matches in two images. Subsequently, important theoretical advances were made by mathematicians at the Technical University of Vienna. An excellent reference for geometry and its relationshipto photogrammetry is a book of Emil Muller on constructive geometry, which appeared in 1923. Muller's assistent and successor Erwin Kruppa established the "structure-from-motion" theorem in 1913. This theorem was rediscovered by Shimon Uliman in 1977

Practical considerations for the use of airborne GPS for photogrammetry

Abstract: The term «GPS photogrammetry» is applied to the use of an airborne global positioning system (GPS) receiver in conjunction with the collection of arial photography. There are two important reasons to use airborne GPS: to perform accurate flight-line navigation, and to reduce the amount of ground control required for the aerotriangulation adjustment. Research has shown that the use of GPS-derived camera exposure centers in aerotriangulation can greatly reduce or even eliminate the need for ground control. A number of successful tests have been conducted in research environments where great care has been taken to control systematic errors, and bundle adjustment programs have been specially modified to incorporate GPS-derived exposure stations

Toward real-time dynamic close-range photogrammetry

Abstract: The goal of the Active Stereo Probe (ASP) project is the on-line recovery of 3D surfaces from stereo images captured using a dynamic binocular robot vision system. In this paper, we present results of 3D surface recovery using scale-space automatic stereo-matching. These results have been considerably enhanced by bathing the scene in textured light provided by the ASP active illumination source. We also describe a two stage approach that incorporates photogrammetric techniques into the ASP system to maintain calibration during dynamic system operation. Direct Linear Transform based calibration provides an initial static calibration. Thereafter, dynamic calibration is maintained by exploiting high resolution encoders to track the systems external orientation parameters and thereby constrain the search space of subsequent bundle adjustment. We expect this strategy to achieve the speed and accuracy required to satisfy many on-line 3D surface recovery applications.

Experiences in GPS photogrammetry

Abstract: Some tests for combined block adjustment with kinematic GPS coordinates of the projection centers have been carried out by the University of Hannover. The photogrammetric data handling has been solved, but up to now the GPS data are more or less disturbed. That means that the photogrammetric data processing has to compensate for such problems. The results of the combined adjustment of disturbed data are satisfying. Due to the considerable cost reduction of the whole process - the number of control points can be reduced to just four - there is a strong request for practical application. A good organization of the photo flight and the selection of suitable hardware components is very important to avoid unnecessary problems

Global image matching and surface reconstruction in object space using aerial images

Abstract: Global image matching is a general model for digital photogrammetry, integrating area-based multi-image matching, point determination, object surface reconstruction and orthoimage generation. Using this model the unknown quantities are estimated directly from the pixel intensity values and from control information in a nonlinear least squares adjustment. The unknown quantities are the geometric and radiometric parameters of the approximation of the object surface (e.g. the heights of a digital terrain model and the brightness values of each point on the surface), and the orientation parameters of the images. Some tests using this approach on real aerial imagery were made. A manually measured digital terrain model was used as reference. The main objective of the tests was to investigate if using more than two images in the global matching would increase the accuracy and reliability of the results. In this paper a review of the approach, the tests and the results are presented and evaluated. Some problems with using this approach on real imagery and practical applications are discussed, and suggestions for future development of the method are made.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Adapting Three-Dimensional Animation Software for Photo grammetry Calculations

Abstract: A new method for computer-based photogrammetry in accident reconstruction is presented. CAD software is used to product three-dimensional models of the site, vehicles, and other objects important in the incident. Objects of known configuration are incorporated into the scene model, and a perspective view is created that corresponds to the photograph. Then the objects of unknown position are added, and these are translated and rotated until they match the photograph. The result is a three-dimensional computer model of the site geometry, from which positional information may be extracted by examining the top, front, and side orthographic views.

Retroreflective target and its method of manufacture

Abstract: The invention relates to a retroreflective target, especially for the inspection, measurement and observation of a surface or for the study of an object or of a cinematic system, comprising a retroreflective external surface (1) which reflects the incident light emanating from any light source, substantially in the same direction as that from which it came so as to permit the observation, either visually or by forming an image of the retroreflected light. The target according to the invention takes the form of a sphere. Application to photogrammetry.

GIS orthographic digitizing of aerial photographs by terrain modeling

Abstract: Spatial data digitized from individual raw aerial photographs are corrected analytically to update a geographic information system (GIS) database. The collinearity correction model is compiled by applying digital terrain data and a suitable base of horizontal control. This method, photo-digitizing, allows spatial databases to be updated from digitizer workstations without photogrammetric equipment and processing. Data entry staff do not require special photogrammetric training. From testing on surveyed ground targets, thee accuracy of photo-digitizing (5.5 ± 3 m) exceeds that achieved with current field data and procedures. Field staff retain ownership of data and control of the update process