study of the interdependence of data compression and image 
quality. 
In addition, WAOSS was also tested inflight. Some airborne 
tests have been flown over brown coal surface mining areas 
and urban regions as well (Fig. 3). Even an inside view of a 
cathedral could be generated demonstrating the wide 
dynamic range of the WAOSS data. 
Laboratory and outdoor test of the flight modules indicate 
that the cameras meet or exceed their design goals. In 
particular the high resolution capabilitiy of HRSC and the 
dynamic range of WAOSS yielded impressive results. Thus 
very high quality image data from Mars mission can be ex- 
pected. 
3. REFERENCE SYSTEMS 
FOR PHOTOGRAMMETRY AND CARTOGRAPHY 
The potential of the combined HRSC/WAOSS experiment 
will open a new era in mapping of the planet Mars. The 
accuracy of point determination and DTM generation will 
considerably improve our existing knowledge. This is why 
there was also a need set new definitions for the reference 
systems to be applied for photogrammetric and cartographic 
activities. 
This issue has been subject to many discussions during the 
meetings of the Photogrammetry and Cartography Working 
Group (PCWG). Finally the following definitions were 
accepted. 
3.1 Planetocentric Coordinates 
The establishment of a geodetic control network, photo- 
grammetric bundle adjustment etc. will be based on a 
planetocentric coordinate system (Fig. 4). Any point P on 
the Martian surface can be described by 
* its planetocentric latitude ©, this is the angle between 
P, the planet's center and the equatorial plane (¢ is 
positive in the northern hemisphere), 
* its planetocentric longitude A, this is the angle between 
the meridian through P and the prime meridian (A = 0) 
through the crater Airy-0 (A counts positive towards 
the east), 
* its distance R, this is the radius vector from the center 
of mass (origin of the system) to the point P. 
3.2 Planetographic Coordinates 
For all mapping activities a reference body fitting appro- 
priately to the shape of the planet need to be defined. 
Following the traditional understanding in mapping science 
and in accordance with the already existing maps, it was 
decided to define planetographic coordinates as the primary 
reference system for mapping. According to the definitions 
generally accepted by the International Astronomical Union 
(IAU) a planetographic system is associated with longitudes 
counting positive to the west. This is why the map coordinates 
of a point P will be 
- the planetographic latitude ¢', this is the angle between 
the normal to the reference surface at P (generally an 
ellipsoid) and the equatorial plane (¢' is positive in the 
northern hemisphere),and 
60 
  
Fig. 2: HRSC test image, acquired in Friedrichshafen across 
Lake Constance. The top image is a small subset of an ori- 
ginal image strip. The lower images show details, namely 
the Santis Peak at a distance of 43 km and a fisher boot on 
Lake Constance. 
Fig. 3: Part of an image strip acquired in July 1995 
during a WAOSS test flight over Berlin 
(after first-order geometric correction) 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
  
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