topic Re: Colormap identifies value as 0 while it is NoData in ArcGIS Pro Questions

Colormap identifies value as 0 while it is NoData

monikat — Fri, 03 Mar 2023 22:42:01 GMT

I have two rasters that have been cropped and masked. One with a colortable (test_ctb.tif), the other without (test_nctb.tif). For the NoData pixels, the one with colortable (test_ctb.tif) identifies its value as 0 while it should show NoData. When I switch to unique values, then both rasters show correctly NoData for that pixel. The color table works fine in ArcMap 10.8.2 though!

Re: Colormap identifies value as 0 while it is NoData

Omar_A — Sat, 04 Mar 2023 04:34:14 GMT

Hi,

You may need to modify the colortable of the raster with the incorrect NoData values in the "Colormap" pane > Edit "Colormap" > Check the "Use values" checkbox and enter the NoData value for the raster. This is to be the same value used by the other raster that has correct NoData values. Try these steps; it might solve the issue.

Thanks,

Omar

Re: Colormap identifies value as 0 while it is NoData

monikat — Mon, 06 Mar 2023 14:39:33 GMT

Hi Omar,

Thanks for the post! I do not see any "Use values" checkbox under Symbology for Colormap? And neither edit option for the Colormap? When I click file Properties > Raster Information NoData Value is 255 which is correct.

And I added that yellowish under the Mask to Nodata, so it correctly finds that NoData, but displays incorrectly its value.

Re: Colormap identifies value as 0 while it is NoData

MelanieM — Thu, 09 Mar 2023 23:37:01 GMT

Hello @monikat,

Esri is now aware of the issue and there has been a bug logged for this specific issue. The bug number is BUG-000156484. There is also a workaround for this problem.

Workaround:

In ArcGIS Pro, open the Geoprocessing pane and search for 'Con' (Image Analyst Tools)
Select the Con tool and fill out the parameters appropriately
- Identify the raster layer in 'Input conditional raster'
- No expression
- Select the same raster as above for 'Input true raster or constant value'
- Insert '0' for 'Input false raster or constant value'
- Choose an appropriate name for 'Output raster'
- Run tool
Export the colormap from the original data layer
- Navigate to the symbology pane with the original data layer selected
- Select more options on the top right corner of the pane
- Select 'Export colormap'
Import the colormap into the new layer
- Navigate to the symbology pane with the new layer selected
- Select more options on the top right corner of the pane
- Select 'Import colormap'
- Select the correct colormap to be imported

Thank you for letting us know!