Originator:
Dr. Eric Eliason USGS Geological Division 2255 North Gemini Drive Flagstaff, AZ 86001 (602)556-7113 ASTROG::EELIASONNSSDC ID: 75-075A-01f/083A-01c
(75-075A-01f) MDIM
This data set contains a digital image map of Mars that is a cartographic extension of a previously released set of CD-ROM volumes containing individual Viking Orbiter Images (PDS data sets VO1/VO2-M-VIS-2-EDR-V2.0 [NSSDC IDs 75-075A-01c and 75-083A-01a] and VO1/VO2-M-VIS-2-EDR-BR-V2.0 [NSSDC IDs 75-075A-01d and 75-083A-01b]).
The data in these earlier data sets are pristine, in 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, however, 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). It contains digitized versions of an airbrushed map of Mars as well as a listing of all IAU-approved feature names.
Special geodetic and photogrammetric processing has been performed to derive rasters of topographic data, or Digital Terrain Models (DTMs). Because the photometric processing used in this MDIM was oversimplified, quantitative radiometric analysis on these data is not possible.
The MDIM CD-ROM collection serves two purposes. First, the image collection serves as a database for interactive map browser applications. Secondly, the CD-ROM set provides a dense delivery medium to build higher-derived cartographic image products such as special map series and planning charts for the Mars Observer Project. This set contains seven volumes.
Volume 1 contains images of the Vastitas Borealis Region of Mars, 373 image files covering the entire north polar region of Mars southward from the pole to a latitude of 42.5 degrees north. Polar Stereographic projection images of the north pole area from 80 to 90 degrees are located in the POLAR directory on this disk.
Volume 2 contains images of the Xanthe Terra Region of Mars, 412 image files covering the region of Mars from 47.5 degrees north latitude to 47.5 degrees south latitude, and 0 degrees longitude to 90 degrees west longitude.
Volume 3 contains images of the Amazonis Planitia Region of Mars, 412 image files covering the region of Mars from 47.5 degrees north latitude to 47.5 degrees south latitude, and 90 degrees west longitude to 180 degrees west longitude.
Volume 4 contains images of the Elysium Planitia Region of Mars, 412 image files covering the region of Mars from 47.5 degrees north latitude to 47.5 degrees south latitude, and 180 degrees west longitude to 270 degrees west longitude.
Volume 5 contains images of the Arabia Terra Region of Mars, 412 image files covering the region of Mars from 47.5 degrees north latitude to 47.5 degrees south latitude, and 270 degrees west longitude to 0 degrees west longitude.
Volume 6 contains images of the Planum Australe Region of Mars, 373 image files covering the entire south polar region of Mars northward from the pole to a latitude of 42.5 south latitude. Polar Stereographic projection images of the south pole area from 80 to 90 degrees are located in the POLAR directory on this disk.
Volume 7 contains the Digital Topographic Map (DTM) of Mars, MDIMs of the entire planet at 1/64, 1/16, DTMs of the entire planet at 1/64, 1/16, and the digitized airbrush map of Mars at 1/16 and 1/4 degrees/pixel.
Volumes 8-13 consist of multi-look color MDIMs at 1/64 degrees/pixel. The regions covered by volumes 8-13 are the same as those covered by volumes 1-6, but the planet-wide coverage is less complete. Each area is covered by three images of the same region, each through a different filter.
Volume 14 contains a planet-wide collection of multi-look color MDIMS, at 1/64 degrees/pixel, in compressed format. This disc also contains full mosaics at a variety of resolutions from the 1/8 to 1/64 degrees/pixel. The images on this volume are stored as 8-bit, paletted color images using the CompuServe Graphics Interchange Format (GIF). Unlike volumes 8-13, data have been pre-stretched for optimal color display.
Each of the first six volumes contains MDIMs of the areas specified at resolutions of 1/256 degrees/pixel (231 m) and at 1/64 degrees/pixel (943 m). Volumes 1 and 6 also contain MDIM coverage of the entire planet at 1/16 degrees/pixel (3.69 km). Each of the six volumes also includes a digitized airbrush map of the entire planet at 1/16 degrees/pixel (3.69 km) and at 1/4 degrees/pixel. The Sinusoidal Equal-Area Projection, is used as the map projection for this image collection. The tiling layout of the 1/64 degrees/pixel digital models is the same on the first six volumes.
Note that the 1/64 degrees/pixel MDIM segments that appear in volumes 1 through 6, are duplicated in their entirety on volume 7. All of the resolution compressions were done by averaging, not by subsampling. A gazetteer of IAU-approved feature names, referenced by latitude/longitude coordinates is included as a table file on each of the seven volumes.