I am creating contours from an Aster DEM in ArcMap 10.1

I see a grid pattern appearing, particularly in areas of dense contours:

enter image description here

I see the same artifact if I create a Hillshade layer so presumably it is a problem in the DEM.

enter image description here

The grid artifact doesn't correspond to the sample size of the DEM.

I am using the original DEM - no resampling or focal statistics.

The DEM has not been reprojected (displayed in the WGS84 UTM projection it was delivered in).

Any ideas about the cause of the artifact?

If so could anyone suggest a workflow (other than resampling/ focal statistics) for removing it?

  • Would you be able to edit your question to include the GIS software and version that you are using, please ? – PolyGeo Aug 28 '14 at 12:30

I believe the gridded effect you are seeing is down to one of two things:

  • How you are displaying the raster and not necessarily anything to do with the base dataset.
  • How you have projected your data

Have a read of this article and this blog page. Bilinear Interpolation seems to be the best choice but is not the default setting.

  • It seems I (wrongly) assumed that the coordinate system was projected - I followed the workflow in the article you included and the artifact is gone. Thankyou very much for your advice! The blog you included was also very interesting. – Peter Aug 28 '14 at 20:45

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