topic Re: Resample or interpolate a 30m DEM to 10m in ArcGIS Spatial Analyst Questions

Resample or interpolate a 30m DEM to 10m

ColinMurray — Fri, 23 Nov 2018 17:14:53 GMT

Hello

I would like to reduce the cell size of a SRTM DEM from 30m to 10m for my analysis with ESA Sentinel 2 imagery.

I'm confused about the difference between the Resample tool and using say IDW in the Interpolation tool set. And also wondering which would be more appropriate to use.

I would assume that I'd want to use IDW interpolation. However, it seems I'd have to convert the current 30m raster to a point file before I can interpolate. Resample does seem to be an interpolator as well but I'm suspicious of it's methods for doing so.

Re: Resample or interpolate a 30m DEM to 10m

DanPatterson_Retired — Fri, 23 Nov 2018 17:42:17 GMT

resampling the 30 m dem to 10m would be best since it actually represents the original interpolation/measurement of the data. Re-interpolating may produce a different surface and that would at best be confusing.

You can't improve on raster data by re-interpolating.

If you are conflicted, aggregate your 10m data to 30m so that it is at the resolution of the coarser set. Compare the two result. Aggregation produces its own set of issues as well, but it is a better alternative than reinterpolating coarser data to a finer scale than it may not represent.

Re: Resample or interpolate a 30m DEM to 10m

ColinMurray — Sat, 24 Nov 2018 14:25:46 GMT

I see what your saying and will try resampling the DEM.

Aggregation from 10m to 30m I will try but but I'd hate to loose that 10m resolution.

Thank you for the reply. It has helped.

Re: Resample or interpolate a 30m DEM to 10m

SteveLynch — Sat, 24 Nov 2018 14:58:16 GMT

I agree with Dan regarding the idea of doing it at 10 and 30 and comparing the results.

Just on a technical note, resampling is also interpolation if you consider, for example, bilinear and cubic convolution.

The topography of the area will also dictate the interpolation/resampling method.

-Steve