Martian Cartography Options

[karolp]

I have recently freaked out a little bit about Martian maps of all sorts. And finally I was astonished with those highly detailed beauties that I list below. Nonetheless. some of them have huge inconsistencies (crater names) easily noticed when we compare the surroundings of Gusev crater. Enjoy:

http://www.ralphaeschliman.com/
http://planetologia.elte.hu/1cikkeke.phtml...arsmapinte.html
http://pubs.usgs.gov/imap/i2782/

[Greenish]

Regarding the map projection & registration, for rover ops, I learned some things when mcaplinger pointed out this MSL document a little while back: https://pds-imaging.jpl.nasa.gov/data/msl/M...CES_PDS_SIS.PDF

For Curiosity, there were some deliberate simplifying assumptions made regarding position plotting on the mission-specific image mosaic. I wonder what the status is for Perseverence... the orthoimages and DEMs at the USGS site (e.g. here) are much larger and more comprehensive from what I can tell, but they may not be exactly what the operations team is using.

[Andreas Plesch]

Regarding the map projection & registration, for rover ops, I learned some things when mcaplinger pointed out this MSL document a little while back: https://pds-imaging.jpl.nasa.gov/data/msl/M...CES_PDS_SIS.PDF

For Curiosity, there were some deliberate simplifying assumptions made regarding position plotting on the mission-specific image mosaic. I wonder what the status is for Perseverence... the orthoimages and DEMs at the USGS site (e.g. here) are much larger and more comprehensive from what I can tell, but they may not be exactly what the operations team is using.

Thanks, that is a very helpful document. I learned that the rover positions are with respect to the center between the center wheels, that RMC means Rover Motion Counter, that the onboard positioning can get refined, and how the stacked system of reference frames is defined. Given this, it seems to me that the coordinates provided in the geojson data are directly from the PDS PLACES (or successor) database. Unfortunately, I could not find direct access to the PDS PLACES database for the Mars2020 (M20?) mission, only previous missions, for a more robustly defined source. For example, it is unclear if the geojson provided latitudes are planetocentric or planetodetic as both are described. But choosing the wrong interpretation for projecting back into the equirectangular projection used for the base map would lead to an obvious mismatch I think.

I am using that USGS mosaic and here is the geotiff CRS:

PROJCRS["Equirectangular Mars 2000 Sphere IAU",BASEGEOGCRS["D_Mars_2000_Sphere",DATUM["Mars_2000_(Sphere)",ELLIPSOID["Mars_2000_Sphere_IAU",3396190,0,LENGTHUNIT["metre",1]],ID["ESRI",106971]],PRIMEM["Reference_Meridian",0,ANGLEUNIT["degree",0.0174532925199433,ID["EPSG",9122]]]],CONVERSION["Equidistant Cylindrical",METHOD["Equidistant Cylindrical",ID["EPSG",1028]],PARAMETER["Latitude of 1st standard parallel",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8823]],PARAMETER["Longitude of natural origin",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["False easting",0,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False northing",0,LENGTHUNIT["metre",1],ID["EPSG",8807]]],CS[Cartesian,2],AXIS["easting",east,ORDER[1],LENGTHUNIT["metre",1,ID["EPSG",9001]]],AXIS["northing",north,ORDER[2],LENGTHUNIT["metre",1,ID["EPSG",9001]]]] - Projected

I think it is exactly the projection described in the PDS pdf, including the sphere radius of 3396190m.

The Where is the rover ? online map uses leaflet and proj4leaflet plugin which indicates that it uses a custom map projection, likely the equirectangular projection, for the tiled base map. The traverse data on the other hand had a crs field indicating potentially use of a terrestrial crs.

I am relying on QGIS/GDAL to convert between CRSs which should be better than trying to do it myself although the conversion is straightforward for this projection.

On a side note, I saw in the MSL PDS archives that there are site specific mesh reconstructions of local topography, presumably based on stereo imagery. It would be cool if Mars2020 could make those available. They are probably generated currently.

I also saw in the configuration data for the online map that there is an option for "site experiences", and that THREE.js is being loaded, a popular web 3d rendering library, presumably in anticipation of such experiences once they are ready for consumption. Something to look forward to.