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

Type of content:: Konferenzschrift

Year of publication:: 1996

Place of publication:: Vienna

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

Identifier (digital):: 1667435949

Reihe:: International archives of photogrammetry and remote sensing

Language:: English

Editor:: Kraus, Karl; Waldhäusl, Peter

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

Contributor:: International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1667437070

Title:: XVIIIth Congress

Scope:: 230 Seiten

Type of content:: Konferenzschrift

DOI:: 10.14463/KXP:1667437070

Year of publication:: 1996

Place of publication:: Vienna

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

Identifier (digital):: 1667437070

Illustration:: Illustrationen, Diagramme

Reihe:: International Archives of Photogrammetry and Remote Sensing (31,B1)

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

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

Contributor:: 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:: THE GEOMETRIC DESIGN OF A VEHICLE BASED 3 LINE CCD CAMERA SYSTEM FOR DATA ACQUISITION OF 3D CITY MODELS Markus Maresch, Peter Duracher

Document type:: Multivolume work

Structure type:: Chapter

support s. Odo- in algo- ementa- nent part inter In envi- onds to around de usu- ight of f street 1 of Wn. ical vere The similarity of the used technology to satellite scanners [Hof88] or aerial push broom applications is given for geo- metric concerns of the principal configuration. The differ- ence though is the fact, that satellite scanners follow a quite smooth path over practically flat terrain with no regular struc- ture, while the facade scanner has to operate along a rough path along assumed planes with the knowledge of regular ver- tical and horizontal edges. The shift of the center of the linear CCD lines from the op- tical axis is shown in figure 4. This is done in accordance to figure 3 to omit recordings of ground regions and to keep the advantage of parallelism between object and sensor plane. 2.2 Requirements and constraints The requirements for this portable recording system are de- fined by the recording constraints and by supporting hardware in practice. They are also defined by the demands for the orientation and reconstruction algorithms and the expected quality for the final data of the city models. Color RGB 24 bits Object pixel size (0.25cm)? .. (2cm)? Stereo angle(s) ¢ ~ 20° Vehicle speed 0.5m/s .. 4m/s Line samples > 250/ sec Facade height 10m .. 20m Facade width 100m min. at one go Distance to facade Sm .. 12m Optical center àm .. 4m Storage recording speed | < 4 M B/sec Luminance < 100 cd/m? Table 1: Requirements and constraints: This ta- ble shows the design background for an experimental recording system. Some of these constraints can not be avoided in practice. The system requirements defined in table 1 also reflect practical concerns for an inexpensive implementation. An experimental prototype showed two more remaining prob- lems related to linear CCD arrays: e Sensitivity: To avoid shadows, hazy weather provides the preferred lighting conditions for recording. Unfor- tunately only few types of commercially available sen- sors allow this short exposure time at the luminance values. e Shift rate: Sensitive sensors usually show low shift rates. Therefore many types of available linear CCD arrays must be excluded from further considerations. The constraints explained above force a reduction in the re- quirements due to the necessary aim of practical, cheap im- plementation. Nevertheless we aim to increase the vehicle Speed as soon as the effect of limiting constraints known so far becomes less important. 123 3 DIFFERENTIAL OBSERVATIONS 3.1 The effect of motion disturbance Considering the principal recording configuration as indicated in figure 2 we face motion disturbance caused by the rough- ness of the street. The need for automatic and robust motion detection and elimination leads to investigations of the effect of motion disturbance. We will develop the theoretical framework for the observable effect of motion disturbance first, and will then discuss the possibilities for the separation of correlated motion distur- bance parameters. |n the next section we will discuss the proposed algorithm for the actual motion detection. 3.2 Exterior orientation The ideal recording path has to be provided by data from geographical information systems a priori at least to an ac- curacy of about 1m. Due to the motion disturbance of the vehicle we have to face a camera path different from the ideal. Each triple line sample has a different exterior orien- tation (Xi, Y, Zt, wt, Pt, fà) for time t. Considering high sample rates of ~4ms a realistic chance for path tracking can be shown to exist, because the orientation parameters in a sequence of samples can be approximated by polynomials [KW86], [Ebn92]. Compared to the interpolation of parame- ters of exterior orientation [MHK94], which relies on operator selected, so-called update points, which are obviously rare, in our case each observation can contribute to a stable recon- struction of the camera location. 3.3 Differential observations For the elimination of motion disturbances of the 6 parame- ters of the exterior orientation the geometric differential equa- tions are discussed. Equations of table 2 from [RPgbg78], [Gru94] were modified to reflect the separation of the cen- tral mass, being the center of motion, and the optical center given by an outrigger (see also figure 2). dx dy dXo | —1 0 dYo | 0 —1 dZo EE = do tet) rz usb SEE doll ev rey pus dk y t or, -T Table 2: Differential object coordinate changes caused by sensor motion, dx and dy change in general. We assume a local coordinate system with origin at the per- pendicular projection of the optical center at the facade. So coordinates x,y, z of table 2 have to be scaled by es and red translated by vector or, + my in practice. 3.4 Perpendicular vertical sensor For vertically oriented linear CCD arrays not all motion pa- rameters are observable, and their effect can not always be separated as there are correlated pairs of parameters. International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996

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