Geodesic option in IDW?

[ehallisey]

Can I use unprojected data with a geodesic option in IDW or other interpolation techniques? I've used geodesic measures in kernel density estimation, but I don't see it mentioned explicitly in IDW Help.

Thanks!

Elaine

[DanPatterson_Retired]

Elaine

https://community.esri.com/community/gis/analysis/spatial-analyst/blog/2019/05/06/introducing-the-ne... 

Handling projections during analysis in Spatial Analyst—ArcGIS Pro | ArcGIS Desktop 

would be worth exploring so you can assess whether geodesic methods are needed.  A suitable projected coordinate system is the preferred norm but obviously affected by the areal coverage of the study area

[ehallisey]

Thank you for the info. In this case, I'm working with data that span the lower 48 states of the US. Though IDW may work well with suitably projected data for a smaller geographic extent, I think this area is too large to get optimal results. Can I assume from your answer that using geodesic measures isn't an option (yet) for interpolation techniques, including IDW, in ArcGIS Pro (or ArcMap)? 

[DanPatterson_Retired]

Not that I can see explicitly stated in the help Elaine... I will flag Steve Lynch‌ who will probably have more specific information.

[SteveLynch · Accepted solution]

The only interpolator that we have to use with global data is EBK in Geostatistical Analyst. It uses chordal distances.

A point to keep in mind with most interpolation techniques is that the weight decreases with distance.