topic Re: Mask extraction of DEM changes data in Data Management Questions

Mask extraction of DEM changes data

UlisesHuerta — Thu, 14 Oct 2010 15:17:14 GMT

Hello,
I have a DEM of Rwanda with values that range from 631 - 4434. When I extract using a mask the highest value changes to 4483. Can someone please help me try to figure this one out?
Thanks in advance,
Ulises

Re: Mask extraction of DEM changes data

RobertBerger — Thu, 14 Oct 2010 15:41:11 GMT

Hi Ulises,

Can you calculate the statistics again for your input to make sure the statistics are correct?

Robert

Re: Mask extraction of DEM changes data

EricRice — Fri, 15 Oct 2010 14:47:58 GMT

Hi Ulises,

I have a couple questions.

1. What version are you using?
2. What tool are you using? There are many ways to do this...
     - Clip tool
     - Extract by Mask tool from Spatial Analyst
     - Export Data from TOC with selected graphic (the mask)
3. Are you snapping back to original DEM?

Eric

Re: Mask extraction of DEM changes data

PeterProkein — Tue, 19 Oct 2010 21:21:30 GMT

Perhaps related, in Arc10, a simple Right-Click -> Data -> Export Data appears to change datavalues as well. Source data is in Erdas Imagine format, target data is an Arc GRID. Source elevation range is -1.264 to 1339.19, target range is -20.567 to 1577.26. Cellsize wasn't changed so no resampling should have happened. Not exactly confidence inspiring.