# What (if any) coordinate systems can be used so that distances can be calculated from coordinates?

I am trying to do some work that involves spatiotemporal latent surface modeling, but an issue that I am worried about is that calculating distance between two coordinates is quite a bit more complicated than just applying the Pythagorean theorem in the latitude and longitude coordinates.

I was wondering if there are any projections (especially for the US) where coordinates can be treated as position on a 2d surface in a way that preserves distances between coordinates? Or if this can't be done exactly, are there projections that almost satisfy this criteria?

I think the simplest way to put this is that I'd like to put my data in a coordinate projection system where 1 unit of shift in the X direction is comparable to 1 unit of shift in the Y direction in terms of distance. This is because I'd like to be able to make isotropic assumptions about smoothing across geography.

I'm using R and the `sf` package with `QGIS` and `GDAL` on the backend in case any answers are software specific.

• You need to evaluate the distances calculated with projected units against geodesic functions, and decide if what you gain by simplicity is worth the accuracy loss. There are a number of CONUS conic projections which may suffice. Dec 3, 2022 at 0:21
• Military Reference Grid System?
– John
Dec 3, 2022 at 13:40