Error/Warning in Reclassify

Question

Hi, everyone.

Last week I started getting an error when reclassifying an Aspect raster that says something like "The input raster minimum/maximum (-1) is out of range.  To ensure a correct reclassification, edit ranges or use a different precision settings in the reclassification dialog box." The result looks correct, but this warning is bugging me (and my students).

I already found an answer to the same question using a table attribute, but that it's not the point. The point is to know why this error happens and how can I solve it.

I'm using ArcGIS 10.6 with the latest patches.

Anyone helps?

DanPatterson_Retired · Answer

So the -1 is a bit of a red herring then.  Something must be getting missed, or it is a 'glitch'

Perhaps rather than reclass, try Con with the 2 conditions

in pseudo...

SE_raster = Con((AspectRaster >= X) & (AspectRaster <= X), 1, 0)

Con—Help | ArcGIS Desktop

Conditional evaluation with Con—Help | ArcGIS Desktop

LuísBaptista · Answer

Hi, Dan.

Thanks for the answer, but that it's not the solution.

I want to reclassify the aspect so I can get only 1 class between SE and SW so I excluded the values -1;0-112.5;247.5-360 and set them to No Data.

I can't tell you exactly if the value in parentheses was -1 or an huge number (that can only be huge in decimals). I don't have here the result or the tools to redo it. But I've done this dozens of times before and never get this result. I've tried with small areas and at national scale and the result is always the same.

I also tried to save the aspect and the reclassify output in file system and geodatabase, but the results is equal.

I always get that warning.

Thanks.

DanPatterson_Retired · Answer

Cells in the input raster that are flat—with zero slope—are assigned an aspect of -1.

So the warning is what do you want to do with flat areas?  Preprocess the aspect and set to nodata and reclass later would be one option