GIS project files are currently being made for the original 13 named craters for which MDIS + MLA snippets have been obtained.  The MDIS crater files were easy enough to obtain, but the corresponding MLA was trickier — north + south lat. for MDIS + MLA are the same as well as the east long., but the west long. values for MLA go from 180 to 360 instead of -180 to 0 as with the MDIS.

Once I realized that, I was able to crop out crater files from the MLA that would have the same dimensions as the corresponding MDIS files as well as be centered over the same crater (unlike in a previous post featuring John Lennon where the MLA image I thought was of Hokusai actually is not!).  Then, it was a matter of making sure QGIS would actually render each MDIS + MLA image on top of each other — easier said than done!

Interestingly, I expected the two maps to be misaligned by 180* (or something similar).  Instead, the maps’ boundaries aligned perfectly but the craters themselves weren’t aligned between the MDIS and MLA data-sets.

QGIS screenshot (MDIS + MLA full)
MLA map overlain on the MDIS map in QGIS; the boundaries match but the craters therein do not.

QGIS screenshot (misalignment confirmed...)

Thanks to some ISIS help from Dr. Neish, the use of “maptemplate &” in tandem with “map2map &” allowed my cropped-out craters to be properly rendered in QGIS under a sinusoidal projection centered upon the crater itself.


Abedin crater file:  images match, now to get rid of those annoying polygons and to begin the actual analysis process.

Now the fun stuff can begin!  Contouring the MLA file for each crater will help me determine the most likely location of each crater’s rim crest low, and from there I’ll be able to correlate to where the melt deposits are located and thus compose, hopefully, a more accurate plot of Mercury’s complex craters for comparison with the Neish et al. (2017) figure concerning the Moon and Venus.

All in due time….