EGDR
MOLA Experiment Gridded Data Record


This is the format used for, amoung other things, the topographic grid data for the mars terrain databases. The files are plain ASCII with 6 columns as follows.

Example
     0.5    89.5  3376055.43  3378187.24  -2149.39    24
     1.5    89.5  3376056.95  3378187.27  -2153.40    22
     2.5    89.5  3376066.28  3378187.30  -2148.07    17
     3.5    89.5  3376010.75  3378187.33  -2216.51    11
     4.5    89.5  3376071.33  3378187.35  -2137.71     8
     5.5    89.5  3376128.38  3378187.38  -2070.54     9
     6.5    89.5  3376168.03  3378187.41  -2033.42     7
     7.5    89.5  3376170.55  3378187.43  -2023.11     6
     8.5    89.5  3376181.59  3378187.46  -2009.45     6
     9.5    89.5  3376189.74  3378187.48  -2002.86     7
    10.5    89.5  3376192.72  3378187.51  -1999.38     7
     :
     :
More details can be found on the NASA sites, in particular, further details on the mars datasets is given below.

Quote

The MOLA IEGDR is in the form of an ASCII table with one row for each latitude-longitude bin, from 90 to -90 degrees latitude and from 0 to 360 degrees longitude. The binned data include all MOLA nadir observations from the Orbit Insertion phase, plus Mapping Phase nadir observations, plus off-nadir observations of the north pole above 86 degrees latitude acquired during spring 1998 and of both poles taken in July 1999. Orbits 355 and 358 of the Orbit Insertion Phase and orbits 10709 through 10716, inclusive, of the Mapping Phase are excluded because solutions for these orbits are deemed to be poor. (Note: subtract 10000 from MOLA mapping phase orbit number to determine the equivalent MGS Project orbit number.) Also excluded are shots more than 1 degree off-nadir (except as noted above), channel 4 returns, and any returns not classified as ground returns, e.g. clouds or noise, according to the SHOT_CLASSIFICATION_CODE. Most observations have been crossover-corrected. The polar observations have not been fully corrected and may be revised somewhat, as the pointing of the instrument is not known as accurately as the range measurement.

The IEGDR may be released at various grid resolutions. Examples are 1 degree latitude by 1 degree longitude bins, 0.5 by 0.5 degree bins, and 0.25 by 0.25 degree bins. The IEGDR file name is in the form IEGnnn_v.TAB, where nnn represents the bin size and v the version. For example, the first release of the 0.5 by 0.5 degree IEGDR is named IEG050_A.TAB.