In summary it can be stated from the simulation studies,
that the synergy effect of image and orbit information is most
effective. It can be expected that the accuracy of the current
ground control network of Mars will be generally imroved by
a factor of ten or more. Still more sophisticated adjustment
procedures, considering also Mars rotation parameters, are
being developed. For details see Ohlhof (1995, 1996).
4.2 Generation of Digital Terrain Models
The Technical University of Berlin is responsible for the fol-
lowing steps of the photogrammetric/cartographic processing
line, e.g. the generation of local, regional and global Digital
Terrain Models (DTM). To fulfill this task an extended area
based least squares matching technique has been deve-
loped (Wewel 1996), which makes use of the entire set of
possible multiple image data (along and across track) in one
process in spite of only two images as it is done in con-
ventional stereo approaches.
Afterwards a Digital Terrain Model (DTM) is derived by mul-
tiple ray intersections making use of the conjugate points
information that resulted from the matching process. In areas
where matching was not sufficiently successful shape-from-
shading techniques will be used to fill the gaps. The irregular
grid of the primary DTM is converted to a regular DTM grid
through appropriate interpolation (Uebbing 1996).
The planimetric reference surface for the DTM is the same
bi-axial ellipsoid which also serves for mapping purposes
(see chapter 3.2). Spacing is performed in a similar way as
it is required for mapping procedures in the sinusoidal pro-
jection. However, heights are handled according to the
definition described in chapter 3.3, i.e. they referr to a tri-
axial ellipsoid as a reference level.
4.3 Orthoimage Generation and Mosaicking
Based on DTM information orthoimages and image mosaics
will be derived by completely automated processes which
have also been developed at the Technical University of
Berlin. While common orthoimage or mosaicking techniques
require manual interactions (e.g. to identify control points
for rectification or to define overlapping regions and border-
lines between adjacent images) these new tools depend only
on the accuracy of the orbit and attitude information.
At the end of the photogrammetric processing line high
quality colour data sets will be generated by merging
multispectral image data of three colour channels and the
high resolution panchromatic data through RGB-IHS-RGB
colour transformations.
The software developed for automatic orthoimage production
and mosaicking has already successfully been tested with
existing planetary data sets. Mosaics e.g. of up to 3000
images of the Moon have been generated from data of the
Clementine mission. For details see Scholten (1996).
5. MAP PRODUCTS
The camera experiment on the Mars96 mission is expected
to provide a great amount of image data. Its mapping poten-
62
tial will by far exceed what has been possible so far. This is
not only because of the regional and global coverage of ste-
reo imagery, the availability of high precision DTM's but also
due to a considerably improved geodetic control network.
Thus, a completely new situation for mapping the planet in
high-quality topographic maps can be envisaged.
The data that is expected to become available during the
mission is applicable for the generation of maps in scales
between 1:500 000 and 1:50 000. The techniques to be
applied for map production are of course digital cartographic
approaches.
This situation gives rise to define the details of new map
series. According to the potential of the camera experiment
and in particular the spatial resolution of the image data the
scale 1:200 000 was selected for the primary map series.
The type of map will be a combination of image map and
topographic map. Therefore the new map series was named
» Topographic Image Map MARS 1:200 000«.
The map projection selected for this project is the Sinusoidal
Projection due to the fact that it is an equal area projection
and a variety of other practical advantages. The polar
regions, however, can only appropriately be mapped in
azimuthal projections. The Lambert Azimuthal Projection has
been selected because it is also an equal area projection.
The parameters of the new map series have been deter-
mined. The entire planet was devided into several latitude
ranges, each with a special map sheet dimension in terms
of latitude and longitude, resulting in more than 10,000 map
sheets. For details see Lehmann (1996).
The working group is well aware of the fact, that shadows
can be a serious problem in the production of image maps
under the conditions of this project. Therefore attempts are
being made to apply »deshading« and »reshading« ope-
rations in order to achieve hill shading effects as they are
desired in topographic cartography. Prof. E. Dorrer and Prof.
G. Neugebauer are working on this problem.
6. OUTLOOK
The camera experiment on the Mars96 mission will provide
a powerful tool for photogrammetric and cartographic appli-
cations of the data. The photogrammetric restitution, the
generation of DTM's and orthoimages as well as the pro-
duction of completely new map series of the planet is a great
challenge for the people involved. They do their best to make
the mission a success. And they hope, that a large scientific
community will considerably benefit from this project.
REFERENCES
Albertz, J., Ebner, H., Heipke, C., Neukum, G., Scholten, F.,
1992. The Camera Experiments HRSC and WAOSS on the
Mars 94 Mission. International Archives of Photogrammetry
and Remote Sensing, Washington D.C., USA, Vol. XXIX,
Part B1, pp. 130-137.
Lehmann, H., 1996. A New Map Series for the Planet Mars
— Concept and Realization of the »Topographic Image Map
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996
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