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Question Submitted 10/30/2008

Q: What contour interval can I expect from a DEM with 30-meter postings?

DN: It is a common misconception to think that DEM resolution and contour intervals are related.  Actually, the relationship is between the vertical accuracy of the DEM and the contour interval.  It is a four to one relationship, so that if the vertical accuracy of your DEM is 10-meters then the smallest contour interval you can extract is 40-meters.  Any contour intervals less than 40-meters are strictly interpolated values.