Checking where values are the same between 2 rasters

Question

I am working in ArcGIS 10.3 and I am trying to discover where the output of two different models agree.

two models were run for the risk of contamination with a carcinogenic toxin. The output of each model was a raster with risk scores of 0, 1, 2, and 4 as the values of each grid cell. the two rasters show some areas with the same score and sometimes the two rasters have different scores for the same area. Is there any way in ArcGIS to analyse the rasters to determine which areas have the same scores and which areas that have different scores on both maps? Im trying to determine areas of uncertainty between the models outputs.

There are also open source tools that do change detection. Here's a good discussion on the subject: http://gis.stackexchange.com/q/33402/8104 — Aaron, Dec 13 '15 at 18:05

score 4 · Answer 1 · answered Dec 13 '15 at 17:56

4

The most comprehensive way is to use Combine in spatial analyst since it produces a classification scheme that allows you see the various combinations of what has remained the same and what is different. If you are solely interested in one class, then other approaches could be used.

answered Dec 13 '15 at 17:56

Thanks the Combine tool worked the best of the suggestions here, although the others worked, just in less detail. – Adrian Skeete Dec 13 '15 at 22:59

score 2 · Answer 2 · edited Dec 13 '15 at 20:23

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I suggest the Equal To tool, found in Spatial Analyst. It compares your two rasters cell-by-cell, creating an output raster. If your two input rasters have the same value, the output raster will contain a 1 for that cell. If the two input raster values are different, the output raster cell will contain a 0.

edited Dec 13 '15 at 20:23

PolyGeo

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answered Dec 13 '15 at 20:02

Stu Smith

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score 1 · Answer 3 · edited Dec 13 '15 at 20:22

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You could try the Raster calculator.

If you put statement "raster_1" - "raster_2", the areas with the same value will have 0 value, other areas gives the difference.

edited Dec 13 '15 at 20:22

PolyGeo

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answered Dec 13 '15 at 20:10

david_p

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Checking where values are the same between 2 rasters

3 Answers3