How to convert accuracy of DEM from 5 decimal places to 2

Question

I had a csv dataset comprising of regular points containing elevation "z-values". I interpolated this using ESRI´s spatial analyst using the IDW method to produce a continuous raster surface. I set the resolution at 12,5 meters, because the points were 12,5 meters apart.

I now have a raster image which gives me values with 5 decimal places. The original data only had 2 decimal places.

My question is...should I round this up to 2 decimal places, because having this level of accuracy doesn´t reflect the absolute accuracy of the image. If I should round up the values, how/with which tool would I do it?

thanks,

Rob

Answer 1

Fundamentally you're right, you shouldn't have excess decimal places because it gives False Precision. I've seen datasets with so many decimal places they're measuring down to the 10's of nanometers!

Unfortunately there's a long thread on the ESRI forums which suggests that ArcGIS at least can't do this - http://forums.esri.com/Thread.asp?c=93&f=995&t=243049

However, you can truncate (via ROUND, CEIL or FLOOR) the decimals entirely which might be a better option given they're interpolated anyway.