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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