topic How do I compare two rasters based on pixel value? in ArcMap Questions

How do I compare two rasters based on pixel value?

EllieHakariAK — Mon, 08 Aug 2022 18:34:28 GMT

What I want to do is take the 2010-2019 and 2040-2049 rasters here and create a new layer that highlights only pixels where the value rises above freezing (0°C) between them. The end result will show where we can expect permafrost to thaw in the next 20-ish years in Alaska.

I've worked with rasters only a handful of times, so I feel a bit out of my element here. Are there any tools, equations, etc. for accomplishing this?

Re: How do I compare two rasters based on pixel value?

DanPatterson — Mon, 08 Aug 2022 19:12:16 GMT

("2040-2049" - "2010-2019) >= 0

Would give you a boolean mask where the above is true (1) or false (0)

You can do this in the Raster Calulator

Re: How do I compare two rasters based on pixel value?

EllieHakariAK — Wed, 10 Aug 2022 19:05:17 GMT

Hello Dan! Thank you for the suggestion. I attempted to perform the calculation, but I received the following error:

ERROR 000539: Error running expression: rcexec()
Traceback (most recent call last):
File "<expression>", line 1, in <module>
File "<string>", line 8, in rcexec
RuntimeError: ERROR 010240: Could not save raster dataset to 2010_2040 with output format GRID.

Failed to execute (RasterCalculator).

I'm not sure why it would be throwing this error. Any ideas?

Re: How do I compare two rasters based on pixel value?

DanPatterson — Wed, 10 Aug 2022 19:55:12 GMT

save it as a tiff in a folder, which is the preferred raster format

eg c:/your_folder/rast_2010_2040.tif

GRID's cant begin with numbers and there a whole load of other restrictions

Re: How do I compare two rasters based on pixel value?

DanPatterson — Fri, 12 Aug 2022 07:43:28 GMT

fixed?