I am new to ISIS and map projection. I just started to work on the LPGRS’s half degree data (https://pds-geosciences.wustl.edu/missions/lunarp/reduced_special.html) using ascii2isis and map2map commands; its original projection is nice to work with (simple cylindrical projection). I want to look into the 5 degree or 2 degree data, because these two data sets are relatively equally-weighted pixels than the pixels in the simple cylindrical projection. I downloaded the data from PDS geosciences node website:
So I am trying to load the 5 degree by 5 degree iron oxide abundance data (or 2 degree by 2 degree) by Lunar Prospector Gamma Ray Spectrometer (LPGRS) into ISIS. I skimmed the documents online but I couldn’t find too much information about this. I wonder if the community has encountered a similar question. Please let me know about any thoughts and if I need to clarify my question more. Thanks!
What is your goal and how do you want to use/analyze the data? If you are just using ISIS to ingest and map project, it could be a little challenging just for that. For ISIS, I think you are on the correct path by looking at ascii2isis.
So some of the data you are interested in has been converted to a more typical raster (image) format already. These data were mostly generated to be used in GIS applications like QGIS and ArcMap or ArcGIS Pro. Some of the data date back to when using the GeoTIFF was not as standardized and the images will likely not that the projection defined in the label. Depending on what tool you are using, that can be accomplished be looking over the readme and for example, defining the correct map projection using ArcCatalog or gdal_edit.py/gdal_translate (GDAL).
A subset of this exact data is also available from Moon Trek, but only colorized. Not the original “data” form. Moon Trek . Once opened, click on the left-top “hamburger” icon (three lines), and search for “prospector”. You will notice those layer are GeoTIFF (although again colorized with available legend).
Note both these data sets appear to be released before the more official PDS ASCII tables were released. But, I do think they are the same data.
So working with PDS3/4 tables can be a little challenging. There should be pretty good support in the Planetary Data Reader (PDR), pds4_viewer, and GDAL’s ogr routines. Learning how to run GDAL’s commandline routines can be tricky so you might want to try to follow this related ASCII table conversion example:
Thank you so much, Trent. Happy to read your question and helpful links and posts! I got much more understanding after all.
Ultimately, I want to use the original equal-area grid coordinates from the 2 and 5 degree data of Lunar Prospector Gamma Ray Spectrometer and project those grid points to some map projection systems without interpolation of grids’ measurement values, and latitudes and longitudes (e.g., simple cylindrical and so on). Specifically, I want to reproduce the image provided in the LPGRS PDS geoscience node website (for example, see the LPGRS FeO map below). Note that in high latitudes of the map, the number of pixels is reduced!
If I read your post and provided materials correctly, many software (ISIS, PDR, PDS4_viewer, QGIS) do not support tab delimited data unless the mapping projection is specified in each row of the data (?). I haven’t explored GDAL but want to reach out to you if my goal makes sense. Please let me know if more clarification is needed for my question and goal. Thanks again!