XVIIIth Congress: XVIIIth Congress

kraus, karl; waldhäusl, peter

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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:: EVALUATION OF DIGITAL CAMERAS FOR PHOTOGRAMMETRIC MAPPING Qassim A. Abdullah, Ph.D.

Document type:: Multivolume work

Structure type:: Chapter

Frame ground coverage (GW) = 1760/0.4 = 4400 feet Recommended average flying height (H) = 0.5 GW/tan20 = 6044 feet Thirty percent side lap between alternate flights ^ 0.3 x 4400 — 1320.0 feet Pixel ground resolution = 4400/2000 = 2.2 feet B/H = 1760/6044 = 0.3 In order to have a priori estimate for the contour interval possible with the digital camera at the calculated parameters the following photogrammetric criteria were utilized (Light, 1990) Piel size 5 HKxB/H 10; bom noiimmaih-datinto A Round (1) where: K = non-dimensional number expressing the degree to which Stereocorrelation can be achieved. (Typical bounds for K are 0.2<K<1.5) 0, = precision of a single height observation which is assumed to be one third of the contour interval (CI) (0, = 1/3(CI)). B/H = the base to height ratio. Substituting B/H=0.3 and K=0.3 (or the parallax errors=0.3 pixel size) in equation (1) will result in the following value for CI. Pixel size = 1/0.3x 03x03 x CI = or CI 4 2.272032 73'- 22m This figure served only as a priori estimate but the possible contour interval should exceed the expectation. 2.3 Data Acquisition The digital aerial photo was acquired during May 1995. The project area is located at Desloge, Missouri and it is characterized by variation of terrain patterns from the very steep slopes along the river banks to rolling and flat areas. The digital frame camera was installed on board the Photo Science, Inc. Piper Navajo Chieftain plane. Four flight lines and a supplementary line were flown at about a 6500 foot flying height which resulted in a slight increase in endlap and sidelap coverage. The data was then processed at the ground facility of Daedalus Enterprise, Inc. at Ann Arbor, MI, where about 100 black and white digital images were obtained in a TIFF format ready for the softcopy workstation processing. A few days prior to the flying, the ground surveying crew established an accurate network of nine control points using GPS techniques and the already established NGS points. Each ground control point was marked with an aerial photography target in the shape of two crossed panels one and a half feet in width and six feet in length. 2 2.4 Digital Photo Triangulation A total of 24 frames that covered the testing site and a total of eight paneled ground control points were used to form the block of photos that is later oriented and triangulated on the Autometric-Vision International softplotter. Considering all the problems that are inherent in the interior parameters of the DFC, the stability of the triangulated block was of concern. Therefore, a smaller block of seven frames with a suitable number of ground controls was used for the purpose of this analysis. The interior orientation was achieved by measuring the pixel of the four corners and the image coordinates system origin was assumed to be at the point of intersection of the two axial lines connecting the opposite corners. Although this assumption is not free from error, it was necessary as no accurate information was available about the principal point location. 2.5 Image matching autocorrelation, and surface modeling The triangulated pairs were then correlated and a digital elevation model was generated using the available tools of the softplotter. The generated surface was then modeled using both the terra model and the Intergraph MGE Modeler. A set of two foot contours was generated. Figure 1 shows a clip from the generated contours. 3. RESULTS AND DISCUSSION In examining the pixel resolution on the softcopy station, the 0.7 m pixel ground coverage seems to be adequate for revealing ground details. The ground targets were easily distinguishable. Due to an appreciable amount of error propagation in the larger block which resulted from camera interior instability, number and distribution of control points (as some of the control points disappeared prior to flying due to local land use activity), a smaller block of seven digital photographs was triangulated and autocorrelated to produce the digital elevation model (DEM). Examining the obtained DEM and the derived contours reveals a great agreement with the set of contours derived conventional ly from a photogrammetric stereoplotter. However, it is found that there is a bias in the digital surface generated from softcopy which is clearly reflected in Table 1. The table shows the data from twenty points selected on a variety of terrain patterns that were measured stereoscopically from the three-dimensional digital stereopair displayed in the softplotter and the same locations were selected and measured in the surface generated by conventional photogrammetry. It is noticed that discrepancy is reduced in magnitude as the evaluated point is closer to a control point. Some other points deviated from the root mean squares of error or bias and that is believed to be either because of the changes in the ground surface as there were a few years between the two mapping dates, or it is because of some trees or brush covering the ground surface. It is also noticed that the discrepancy pattern changes considerably at the step slope at the river banks as the correlation technique faces more ambiguities due to slope relief and dense tree coverage. International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996 The stu frame photog develo} technic The stu digital a mapp param proved 4000x essenti triangi proces to enh: The au offerec

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