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A NEW MARS DIGITAL IMAGE MODEL (MDIM 2.1) CONTROL NETWORK 
B. A. Archinal"', E. M. Lee", R. L. Kirk?, T. C. Duxbury," R. M. Sucharski*, D. A. Cook", and J. M. Barrett" 
"U. S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, Arizona 86001 USA — barchinal@usgs.gov 
°Jet Propulsion Laboratory, 4800 Oak Grove Drive, M/S: 264-379, Pasadena, CA 91109, USA - 
Thomas.C.Duxbury@jpl.nasa.gov 
Commission IV, WG IV/9 
KEY WORDS: Extraterrestrial, planetary, Mars, mosaic, photogrammetry, cartography, remote sensing, exploration 
ABSTRACT: 
The U.S. Geological Survey has recently completed a final revised version of its 231 m/pixel global Viking image mosaic of Mars 
that has substantially improved geodetic accuracy compared to versions released in 1991 and 2001. This mosaic, known as MDIM 
2.1, is currently available in the USGS ISIS file format (see http://astrogeology.usgs.gov/Projects/MDIM21/) and will be formatted 
and submitted to the NASA Planetary Data System (PDS) in the near future for archiving as a single -5-MB DVD volume. 
Positional control for MDIM 2.1 comes from a new geodetic/photogrammetric solution of the global Mars Mariner 9 and Viking 
image control network. The details of this network solution are described here. This network incorporates 1,054 Mariner 9 and 
5,317 Viking Orbiter images. Accuracy of the new solution is improved primarily as the result of constraining all 37,652 control 
points to radii from Mars Orbiter Laser Altimeter (MOLA) data and adding 1,232 "ground control points" whose horizontal 
coordinates are also constrained by MOLA. The MOLA data are believed to have an absolute accuracy on the order of 100 m 
horizontally. Additional improvements result from use of updated timing and orientation data for the Viking Orbiter images, 
improved rescau measurements and hence distortion correction of the images, and careful checking and remeasurement of control 
points with large residuals. The RMS error of the solution is 15.8 um (71.3 Viking pixels, ~280 m on the ground). The IAU/IAG 
2000 coordinate system is used for the network and the mosaic. 
I. INTRODUCTION 
USGS has completed a new version of its global Mars 
digital image mosaic. This version is known as MDIM 2.1 
(Kirk, et al, 1999, 2000, 2001), and is now available at 
http://astrogeology.usgs.gov/Projects/MDIM21/. As part of this 
process we completed a new photogrammetric solution of the 
global Mars control network. This is an improved version of 
the network established earlier by RAND and USGS (Davies 
and Arthur, 1973; Davies and Katayama, 1983; Wu and 
Schafer, 1984), as partially described previously (Archinal, et 
al, 2002, 2003). We describe here the details of this network 
solution. 
The MDIM 2.1 mosaic itself has many improvements over 
earlier Viking Orbiter (VO) global mosaics. Geometrically, it 
is an orthoimage product, draped on the Mars Orbiter Laser 
Altimeter (MOLA)-derived radius model, thus accounting 
properly for parallax distortions in the commonly oblique VO 
imagery. Via the network being described here the mosaic is 
tied to the newly defined IAU/IAG 2000 Mars coordinate 
system (Duxbury, et al., 2002; Seidelmann, et al., 2002) via ties 
to MOLA data. Thus, MDIM 2.1 provides complete global 
orthorectified imagery coverage of Mars at the resolution of 
1/256? (or -231 m) of MDIM 2.0, and is compatible with 
MOLA and other products produced in the current coordinate 
System. Visual inspection of the entire mosaic confirms that 
mismatches between adjacent images and between images and 
overlaid MOLA contours, are almost everywhere less than one 
pixel, with maximum errors approaching 4 pixels (71 km) in 
only a few, relatively featureless areas. Images in the 
monochrome mosaic have variable but generally large solar 
incidence angles and have been highpass-filtered to suppress 
  
* 
Corresponding author. 
863 
albedo variations and normalized to emphasize and to equalize 
the contrast of topographic features. Improvements to the 
surface/atmosphere photometric models used result in 
significantly better uniformity and dynamic range than previous 
versions of the mosaic. The equidistant (cylindrical) projection 
is used for the mosaic, which is divided into files corresponding 
to the 30 MC-quadrangles of the Mars 1:5M map series. For 
convenience, each polar quadrangle is provided as two sections 
in equidistant projection and also as one file in polar 
stereographic projection. 
2. CONTROL NETWORK IMPROVEMENTS 
Improvements over previous Mars control networks are as 
follows. 
New IAU/IAG 2000 coordinate. svstem. The IAU/TAG 
Working Group on Cartographic Coordinates and Rotational 
Elements of the Planets and Satellites has adopted new 
constants, which define the Mars body-fixed coordinate system 
for locations on Mars. The constants as adopted were 
recommended via the NASA Mars Geodesy and Cartography 
Working Group to the IAU/IAG WG (Duxbury, et al., 2002; 
Seidelmann, et al, 2002). The changes include the 
specification of new constants to define the spin (e.g. Wo 
- 176.630?) and pole position of Mars. 
New derivation of VO image acquisition information. New 
values for the exposure epochs and derived camera pointing and 
spacecraft position information have been determined by NASA 
NAIF personnel (Semenov and Acton. 1996a; 1996b). These 
values have been adopted for use in the control solution here for 
all VO images (except for images FSC 39151122, 52128638,