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:: 1667437070

Title:: XVIIIth Congress

Scope:: 230 Seiten

Year of publication:: 1996

Place of publication:: Vienna

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

Identifier (digital):: 1667437070

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(31,B1)

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 Primary Data Acquisition

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 Primary Data Acquisition

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 Primary Data Acquisition

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 Primary Data Acquisition

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:: A CALIBRATION PROCEDURE FOR CCD ARRAY CAMERAS Kerry Mclntosh

Document type:: Multivolume work

Structure type:: Chapter

) by the 1staffar, ted, to it focal late as tension The red the .ogitech > larger ingths. each of lS were sitioned io from 1e self- 1995a). camera | period each of 'eraged r use in of the ured to ad to in age the images jets. A lly no y have ) array or the e, an vhether )orated solated le not is Non- sult of 1 for a argets. digital et, the target, . This at, e (GV) nd the j. All jnored. wn for ith the Id level Three different methods of weighting the pixels were used, being binary (Bl), grey value (GV) and grey value squared (GV^2). The binary method applied a weight of one to each pixel, the grey value method weighted each pixel by its grey value and therefore, the brighter the grey value the more importance was put on the pixel. The grey value squared method used the square of the grey value at the weight to be applied, thus exaggerating the effect as described in the grey value method. Each method produced a separate set of observations and each was processed through the bundle adjustment. The results from each method have been tabulated in Section 5. However, only the binary results have been graphed in Figures 5, 6, 7 and 8 as the results from each method were very similar. The program described above was customised to output files in the format compatible with the bundle adjustment being used. Three bundle adjustment programs were used initially for comparisons, with SPGA (Fraser, 1982) eventually being the sole bundle adjustment used as it was flexible, fast and efficient. Prior to processing the observations in the bundle adjustment, the decentering distortion parameters P1 and P2 were determined using a plumbline lens calibration. These values were used as initial values in the bundle adjustment, to overcome the correlation problems with the offsets to the principal point, as previously mentioned. 5. RESULTS The results from the calibration procedure have been tabulated and graphed in this section and include the calibration parameters for each camera, an analysis of the benefits of averaging images from video cameras, and an analysis of the benefits of radiometric corrections for ‘bad’ pixels and a comparison of the suitability of each camera for close-range photogrammetric measurement. The calibration parameters for each camera are shown in Table 4. This table includes: the root mean square of the image coordinate errors in x and y; the focal length; the offsets to the principal point in x and y; lens distortion parameters K; , Ke , P; and P» ; and the degrees of freedom from each bundle adjustment. From this table, it can be seen that the Single Frame of the Right Philips camera is only marginally worse in image coordinate RMS than the averaged binary, GV or GV squared, however, the averaging does improve the visual quality of the images, removing phase patterns and line jitter. The focal length was determined consistently for each camera. The Right Philips camera was shown to have a relatively large x component in the principal point offsets. The final values for P; as shown in Table 4 vary by only 5-1096 from the initial values determined by the plumbline lens calibration. The radiometric investigation, as described in Section 3.2, determined that there were no 'bad' pixels in these digital still cameras, and 'bad' pixels found in the analog video cameras were more due to sampling and signal transmission than problems in array. This was 141 concluded after many images were acquired to find the 'bad' pixels in the video cameras, and the results were not consistent, but changed with each image. The lens distortion parameters are graphed in Figures 5, 6, 7 and 8 in Section 5.3. The resultant values for the binary, grey value and grey value squared methods were all very similar, as can be seen in Table 4 and only the results of the binary method are graphed. The large radial distortion of the Apple Quicktake and the Logitech Fotoman should be noted. At a radial distance of 2mm, it is equivalent to a shift of 2 pixels, and at the edges of the array amounted to approximately 6 to 7 pixels. This would have to be considered when using the cameras for photogrammetric applications. Any targets or objects to be measured would best be situated close to the centre of the image to ensure the best results. 5.1 Statistical Results of Target Centroiding. Camera Average Average Average Pixels Maximum Minimum Threshold above GV GV (0-255) Threshold Left Philips 253.54 6.92 167.19 117.10 Right Philips 253.79 2.92 165.72 131.48 Apple Quicktake 254.55 1.18 159.76 24.19 Logitech Fotoman 255.00 12.76 170.98 29.38 Table 2. Statistical Results of Target Centroiding As referred to in Section 4, Table 2 shows that the contrast between the targets (average maximum grey value) and the background (average minimum grey value) on the images was very high, which is beneficial for the centroiding of the targets. 5.2 Additional Parameters. See Section 3.1 for a mathematical description. Camera Di b2 Ds ai Left Philips Binary 0.246E-3 0.0298 ** 0.452E-3 0.202E-2 * GV 0.274E-3 0.0298 ** 0.351E-3 0.221E-2 * GV^2 0.259E-3 0.0298 ** 0.427E-3 0.221E-2* Right Philips Binary 0.270E-3 0.0298 ** -0.302E-4 0.173E-2 * GV 0.269E-3 0.0298 ** -0.859E-4 0.174E-2 * GV^2 0.256E-3 0.0299 ** -0.721E-4 0.171E-2 * Single Frame 0.112E-3 0.0298 ** 0.137E-3 0.191E-2 * Apple Quicktake Binary 0.273E-4 0.518E-4 -0.331E-4 -0.380E-4 GV 0.233E-4 0.448E-4 -0.210E-4 -0.484E-4 GV^2 0.267E-4 0.315E-4 0.249E-5 -0.418E-4 Logitech Fotoman Binary 0.698E-4 0.729E-4 -0.716E-4 -0.933E-4 GV 0.689E-4 0.752E-4 -0.815E-4 -0.894E-4 GV^2 0.716E-4 0.720E-4 -0.770E-4 -0.830E-4 * Significant ** Very Significant ( Significance determined by Fisher statistical analysis, see Fraser, 1982) Table 3. Additional Parameters. The most notable additional parameter in Table 3 is that of b» for the Philips cameras, showing that the actual size of the pixel in the y direction is 396 different from the initial value used. International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996

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