| Data Set Abstract |
This digital image map of Mars is a cartographic extension of a
previously released set of CDROM volumes containing individual
Viking Orbiter Images (PDS volumes VO_1001, VO_1002, etc.). The
data in the latter are pristine, in the sense that they were
processed only to the extent required to view them as images.
They contain the artifacts and the radiometric, geometric, and
photometric characteristics of the raw data transmitted by the
spacecraft. This new volume set, on the other hand, contains
cartographic compilations made by processing the raw images to
reduce radiometric and geometric distortions and to form
geodetically controlled Mosaicked Digital Image Models (MDIMs).
(Because the photometric processing used in this MDIM was
oversimplified, quantitative radiometric analysis on this data is
not possible.) It also contains digitized versions of an
airbrushed map of Mars as well as a listing of all IAU-approved
feature names. In addition, special geodetic and photogrammetric
processing has been performed to derive rasters of topographic
data, or Digital Terrain Models (DTMs). The latter has a format
similar to that of the MDIM, except that elevation values are
used in the array instead of image brightness values. The Mars
DTM exists in its entirety on Volume 7. Finally, Volume 7 has a
listing of SPICE files derived for the Viking images used in the
MDIM and the DTM. These files contain updated camera orientation
matrices for each of the frames. The matrices are by-products of
the photogrammetric processing for the control network required
to compile the MDIM and the DTM. |
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