The exact values for the axes which define the shape of 
the reference body will be defined and fixed prior to the 
processing phase. 
4. CARTOGRAPHIC CONCEPT 
FOR THE NEW MAP SERIES 
The guidelines for the new map series of the planet Mars 
have been subject to many vital discussions in the 
working group. As a result of these activities it was 
decided that an equal-area map projection should be 
applied. Finally the Sinusoidal Projection with its useful 
mathematical and graphical features was selected for this 
purpose, also because of its properties and the easy 
transition between the formats of the digital data and the 
printed maps. 
The main attributes of the Sinusoidal Projection are: 
* |tis an equal-area projection. 
The central meridian is a straight line; all other 
meridians are shown as equally spaced sinusoidal 
curves. 
* Parallels are equally spaced straight lines, parallel 
to each other. 
* Scale is true along central meridian and along all 
parallels. 
The polar regions however can not be mapped appro- 
priately by the Sinusoidal Projection. Therefore the 
Lambert Azimuthal Projection, which is also an equal area 
projection, will be applied in the regions between 85° and 
90° north and south. 
  
  
  
  
  
Fig. 1: Sinusoidal Projection for planet Mars, represented as a principle draft in map scale 1:130 000 000 
The subdivision of the Martian surface into individual map 
sheets will follow the planetographic coordinate system 
(Albertz et al. 1996). Latitude and longitude degree values 
are stated in planetographic coordinates with the longi- 
tudes counting positive to the West. 
However, for some purposes — especially if it is referred to 
the digital data — the planetocentric coordinate system 
can be useful. This is why the planetocentric coordinate 
system will also be integrated in the maps as a secondary 
system with the longitudes counting positive to the East. 
The selection of the map scale requires considerations of 
many different aspects. The scale of a map series has 
some serious consequences concerning the planimetric 
accuracy, selection of objects and generalization. And it 
causes the graphical efficiency of the cartographic re- 
presentation and the structure with regard to the content. 
Finally, in this case, the appropriate map scale is directly 
interrelated with the resolution of the image data expec- 
ted. 
Following such aspects the primary map scale for the pro- 
ject has been defined to be 1: 200 000. This is a com- 
promise considering the spatial resolution of the image 
data, i.e. up to 12 m for HRSC (High Resolution Stereo 
Camera,) and a variety of pragmatic aspects as well. One 
criterium was also that the scheme of the map series in 
1:200 000 can easily be used as the basis for the gene- 
ration of more detailed maps in the scales 1: 100 000 or 
1: 50 000. The title of the new series will be: 
»Topographic Image Map MARS 1:200 000«. 
Conventional line maps can not be useful under the 
topographic conditions of the Martian surface. Therefore 
the map will be produced as a Topographic Image Map, 
i.e. the basic information is the orthoimage, supplemented 
by topographical names and all necessary specifications 
with regard to the map frame and the entire marginal 
annotations. Furthermore, the image map will contain 
terrain relief informations in the form of contour lines and 
spot heights. The equidistance of the contour lines must 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
  
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