Bring back Spatial Analyst Merge tool

08-22-2013 09:57 AM
Status: Open
Labels (1)
MVP Esteemed Contributor

At 10.0, the Map Algebra merge function was abolished in favor of Mosaic and Mosaic To New Raster.

Mosaic and the Mosaic To New Raster model tool are very functional -- but these functions are not available inside the map algebra syntax for efficient use with the Raster Calculator and Python.

Funny that Mosaic Dataset functions support this - but not arcpy map algebra.

The two workarounds I know of are 1) use Con and IsNull to grab the first non-NoData cell  or 2) use SOMA or MOMA.

Please bring it back as a tool (maybe something like Merge Rasters in the Local toolset?)

ArcGIS Forum post on this topic

More thoughts. I say "we" because I'm passing on concerns I share with the people I support!

Why not just use the Mosaic and Mosaic To New Raster tools? What's the "use case"?
  1. The mosaic tools do not respect the environment like local operators do. This breaks the arcpy map algebra experience.
  2. There are efficiency gains in delayed processing (nesting map algebra-capable tools) that we don't get using the Mosaic tools.
  3. The Mosaic tools are difficult to use in arcpy map algebra workflows because of the complexity added by the NoData and ignore values, which are handled differently than the map algebra defaults. Mosaic To New Raster is especially problematic due to bit depth issues, I usually run two tools (Create Raster Dataset, Mosaic) to ensure the data will not be scrambled. A local toolset "merge" tool would just be simpler.
I understand the need for the complex Mosaic tools, because of special requirements working with geodatabase rasters and very large datasets. However, we are missing the simple, efficient and straightforward merge tool in the arcpy map algebra workflow.
GeoNet forum link (same thread more direct than the old link)
How to merge raster files in ArcGIS?

Also see:
Implementing merge() in ArcPy map algebra

Still want it. Maybe add "FIRST" and "LAST" to Cell Statistics? This is an alternate workflow to the Mosaic tools, which are limited in their support of the GP environment settings.