XVIIIth Congress: XVIIIth Congress

Kraus, Karl; Waldhäusl, Peter

Bibliographic data

Multivolume work

Persistent identifier:: 1667435949

Title:: XVIIIth Congress

Sub title:: Vienna, Austria 1996

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667435949

Language:: English

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1667438379

Title:: XVIIIth Congress

Scope:: 449 Seiten

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667438379

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(31,B2)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist anhand des Copyrightjahrs ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: TOWARDS AN OPERATIONAL DIGITAL VIDEO PHOTOGRAMMETRIC SYSTEM FOR 3-D MEASUREMENTS E. Tournas, [...] Dr. A. Georgopoulos, [...]

Document type:: Multivolume work

Structure type:: Chapter

Since ie two tem is inates rsors. otions kward ys the Lipton tively, ystem licates e two button S way / most ftware r. The initially e, the "CPU. ng the ement 'ertical image linates e area osition rsor is ding to (7) on and sors in e. The olution BLANK (8) ited by ditional mages, nts to of this ‚a 1GB 120 Hz talEyes a major ve is to juakes. cultural rone to For the above purpose models of ancient monument parts are subjected to seismic tests using the 6DOF earthquake simulator of the Laboratory of Earthquake Engineering of NTUA. Since the movement in space of the test objects would be rather unpredictable continuous monitoring was required. Hence stereoscopic video was employed and the system described has been developed. The details and the first results of these experiments have been presented elsewhere (Georgopoulos et al. 1995). A brief description will be given here in order to present the applicability of the system. The initial tests involved research into all aspects of the experiments. Namely the video cameras to be used, the construction of the whole setup and the algorithms employed in order to achieve the best possible results. The first simulation experiment was taped using two commercial camcorders. One was a SONY Handycam 10x Video 8 AF with 310.000 pixels and the other a SONY Handycam Pro Video 8 AF (V90) with 440.000 pixels. Around the object and independently thereof a test field was setup with 16 premarked targets. The targets were black circles on white background, approximately 30 mm in diameter. In addition three targets were attached on the object itself, in order to enable the determination of its displacements. The co-ordinates of the targets were determined using a Leica T1010 electronic theodolite equipped with a Leica DIOR 3002S EDM, with an accuracy of £3 mm. The two cameras were positioned on tripods at a distance of 5 m from the setup with a base of 0.70 m, thus providing a base-to-distance ratio of 1:7. Imagery was acquired simultaneously with both cameras and was recorded on VHS 8mm tapes. The frames were grabbed using the Screen Machine Il from FAST Electronics frame grabber with a resolution of 736(H)x560(V) pixels. This commercially available frame grabber has the usual standard features and is escorted with an image editing software with rather limited capabilities. In order to overcome certain algorithmic problems involving two different cameras into the calculations, a second series of experiments was conducted with two identical Panasonic K900 VHS video cameras. The same targets were used and they were measured with greater accuracy using only electronic theodolite measurements from two stations. Their co-ordinates were determined with the help of intersection in space with a final accuracy of +1 mm. In another experiment (Figure 3), where a 1:3 model of a Parthenon pillar consisting of eleven cylindrical rings was tested two identical professional Beta video cameras were used. These cameras were offered by a major Greek commercial TV Channel and were genlocked specifically for this experiment in order to produce absolutely synchronised frames. They were able to record 50 frames per second, thus increasing the sampling rate of the moving object and the amount of the data stored. Several algorithms were either developed or used from previous work. These algorithms involved mainly a specially developed target location algorithm, a suitable camera calibration procedure and the necessary calculations for determining the ground co-ordinates of the points of interest. There were three presignalised points on each pillar ring. By calculating the co-ordinates of these targets in space the absolute position of each one of the object blocks would be determined. This determination was carried out both monoscopically, for the case where the object was forced to Swing in one plane, and stereoscopically. In cases the pillar would perform displacements in 3D space, the object co-ordinates of the observed points are calculated by a two camera triangulation algorithm. Image co-ordinate measurements of the points of interest are performed 115 automatically on simultaneous views of the object in order to avoid manual identification of the targets on each frame. Simultaneity is achieved by matching the frames with the same time clock indication. Since absolute synchronisation of the two cameras in the initial experiments required special hardware, which was not available, the synchronised frames were manually determined. Although the proposed method is very simple, many problems may occur in practice. The most important problem is that the clock is not clearly recorded in all video frames. Hence, due to image deterioration in certain cases it was necessary to pick frame pairs with frames having a time difference of as much as 0.05 sec. This was, however, considered as having little effect in the final result. Of course there was no synchronisation problem the case of the experiment taped with the two genlocked cameras. The image co-ordinates of the observed pillar points are introduced into the computation as tie points with unknown positions. For each tie point 3 additional unknowns and 4 observation equations are added. A RMS error from the comparison between the object points' co-ordinates and the co-ordinates computed by the triangulation was calculated. Concerning the first experiment with the two SONY cameras, the observed errors were 4 mm in the X and Y directions and 8 mm in the Z direction. The results are better in the case of the two Panasonic KS00 cameras, where the observed errors were 1.5 mm in the X and Y directions and 4 mm in the Z direction. These results are quite encouraging considering the hardware -6 -8 : ui 0.00 2.00 4.00 sec wa a wl UDECK —— CONV. METHOD ———UWMIDEO Figure 4 used. Moreover the amelioration of the final accuracies in the case of the second experiment is not a result of the different cameras used, but of the better accuracy of the measured control points’ co-ordinates. After the calculation of the co-ordinates of the pillar points for the whole duration of the experiments a comparison was attempted in order to assess the relative and absolute precision of the method. The comparison was performed with the similar results obtained from the conventional displacement meters measurements of the same experiment. Moreover the International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996

Access restriction

Copyright

fullscreen: XVIIIth Congress (Part B2)

Multivolume work

Volume

Chapter

Table of contents

Cite and reuse

Volume

Chapter

Image

Image fragment

Citation links

Citation recommendation