topic Re: How to fix wide-stretched projection near poles? in Coordinate Reference Systems Questions

How to fix wide-stretched projection near poles?

RigelAltair — Tue, 25 Jun 2019 11:28:00 GMT

This is a clip from https://astrogeology.usgs.gov/search/map/Moon/LRO/LOLA/Lunar_LRO_LrocKaguya_DEMmerge_60N60S_512ppd, specifically from 11ºW 43ºS location which is attached here. Is there a way to change the projection to be from those coordinates? (11ºW 43ºS) or at least fix the stretched image (looks wider) without messing up the DEM data?

Thank you in advance!

Re: How to fix wide-stretched projection near poles?

DanPatterson_Retired — Tue, 25 Jun 2019 12:17:44 GMT

Equirectangular projection - Wikipedia

So basically not the greatest coordinate system and definitely not one that requires planar measures for terrain derivatives.

This blog by Simon Kettle says there are no projected coordinate systems

https://community.esri.com/groups/coordinate-reference-systems/blog/2017/10/16/planetary-coordinate-reference-systems-the-moon

Perhaps Simon Kettle‌ or Melita Kennedy‌ can provide recommendations

Re: How to fix wide-stretched projection near poles?

MelitaKennedy — Tue, 25 Jun 2019 16:41:43 GMT

Any type of reprojection is going to mean resampling the cell values so there will some changes. What kind of analysis do you want to do with the data? Or is it more for visual effect? For equal areas, equal earth or Eckert IV. For a compromise (not fully equal area or conformal), Robinson or Winkel Tripel.

I don't know if you've already visited it, but check out PIGWAD (I think the name has changed), which may have some suggestions or data products.

Melita

Re: How to fix wide-stretched projection near poles?

RigelAltair — Tue, 25 Jun 2019 17:35:44 GMT

Is to be able to make the crater look more realistic (circular), so later I can extract the elevation points with their x and y coordinates. Did the "Re-projection" under Raster Functions to different coordinates and see if they change, so far after running the function the crater remains ellipsoid. Also, I tried to open the .jp2 under PS CC but is not compatible (that way transformation can be done manually and is much easier).

What worked so far is going to Map -> Properties -> Mercator and it looks pretty much circular. Is there a way to set an specific point on the map and project from it?

Attached, for example ArcGIS automatically sets the raster data in their correct coordinates, however, the data I need is cropped and cannot be set together.

Re: How to fix wide-stretched projection near poles?

MelitaKennedy — Tue, 25 Jun 2019 19:08:13 GMT

If I understand correctly, sure. Try using azimuthal equidistant and customize it so the center point is the center of the crater.