MosaicToNewRaster

[mjrubino]

ArcPro 3.1.1

Windows 11

I am trying to use the MosaicToNewRaster tool to mosaic to rasters (tiffs). The first raster has cell values of 1 and NoData. The second raster has cell values of 2 and NoData. They are both 2-bit and have NoData values set to 0. When I use the MTNR tool with the SUM method, overlapping cells are NOT 3 (as they should be) but retain the value of the first raster in the list (1 if the first raster in the list is 1-NoData, or 2 if the first raster in the list is 2-NoData). Essentially, the sum operator is not working. Incidentally, I also tried the MAXIMUM method and that did not work either. Additionally, I have tried the Mosaic function wherein I first create an empty raster and mosaic the two rasters into the empty one. This does not work either.

This tool is working using ArcGIS 10.x, so I'm convinced this is a bug in the newest version of the ESRI Arc series (spatial analyst specifically). Anyone else have this problem?

My work around (which adds a considerable amount of processing time that I would prefer to avoid) is to reclass the NoDatas in each initial raster to 0s and then mosaic them. This appears to function properly.

[mjrubino]

I figured out what the problem was with MTNR. Each of my inputs had a colormap associated. It appears that the "mosaic color map mode" parameter is interfering with the SUM parameter and only using the values in the color map of the first raster in the list to mosaic -- the default. Ignoring this parameter does not fix the issue. So, do not try to mosaic rasters with colormaps if you want the process to calculate a statistic across the input rasters at overlapping locations.