Almost-Arctic Equidistant

[DarrenWiens2]

Here’s the situation: need to calculate distances from a central point to several destination points. The distances would often cross a UTM boundary (usually by a few hundred km). The Polar azimuthal equidistant projection is attractive, but apparently distorts near 60 degrees, which is also near the central point. I figured I could use a custom version of Polar azimuthal equidistant, centred at the central point. My confusion is that the distances calculated in the custom projection are much more similar to the UTM distances than the original Polar CRS. So, if I accept that the UTM distances are distorted, that would lead me to believe that the custom CRS distances are also distorted.

I suppose my main question is: how do I create a “good” equidistant projection, at about 60 degrees N?

Please help, Melita Kennedy‌! 

[DanPatterson_Retired]

Darren, besides arcpy geodesic options, or in the standard polyline tool, you could just use Vincenty if you only have a few to do

[DarrenWiens2]

Thanks, Dan_Patterson‌. I was asking for a friend massaging data into a format suitable for their specific R package-dictated needs, which I gather relies on coordinates, not distances, from which it calculates distance via Pythagoras. In any case, they compared all the distances described above against geodesic, and both UTM and custom Polar azimuthal were extremely close to geodesic, so either of those seem adequate, as opposed to stock Polar, which seems to have more much more distortion near its edges than the distortion of almost completely crossing the next UTM zone. Thanks again.