Quick way to "mosaic" rasters with nodata areas

Discussion created by csny490 on Jun 27, 2013
Latest reply on Jun 28, 2013 by csny490
This is a long standing issue that I have always dealt with by reclassing the NoData pixels to 0s or using the Mosaic Tool, and now it's really starting to bug me, so but here's the issue:

I have two rasters (both of the same extent/cellsize/cell alignment) where, for say some random col/row, one raster has NoData and the other raster has a value of 2. I want to return a raster that overrides the NoData with a 2. So in other words, have an output raster that ignores the NoData (unless it's no data in both the rasters). So like: Nodata + 2 = 2. Of course normally the "correct" answer is NoData.

What is the best (fastest) way to ruturn a composite raster where the data values override the NoData values?

The mosaic tool works, but is kind slow, and reclassing the NoData's to 0s first and then summing also work, but again is relatively slow.

There's got to be a faster way, right?