I have two raster layers. Layer A has a cell size of 1020 m. There are 31,840 rows in the attribute table, each corresponding to a different 1020 m x 1020m cell. Layer B has a cell size of 30 m. The attribute table associated with this only has two entries - value (0,1) and count of value.

I want to combine the two layers such that I have the ID of the 1020 m x 1020 m cell from layer A that spatially overlaps the values from layer B. After reading How to find the area of raster values within polygon zones? I used the "combine" tool. But the number of rows in the output are not what I would expect. Instead of the new layer having the same number of rows as layer A (31,840), there are considerably fewer (only ~22,000). The graphic below shows an example - two similar areas with roughly the same amount of missing data in layerB. An output from the Combine tool was produced for one of these areas, but not for the other! I don't understand what could have gone wrong! Any ideas?

Left: two areas with similar amounts of missing data. Right: Only one of the two areas got a result from the Combine tool.

closed as off-topic by PolyGeo Feb 4 '17 at 5:45

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  • 1
    Is there an area where the two rasters don't overlap or nodata pixels are present? Consider the Zonal Stats and Zonal Stats as Table tools as an alternative, they may be more useful in your end result than combine tool. – Michael Stimson Sep 9 '14 at 23:46
  • There are no areas where they don't overlap. There are areas where layer B has no data, but there are many areas where that is the case yet I still get an output from the Combine tool. I will try the zonal stats. – user3251223 Sep 9 '14 at 23:56
  • the zonal statistics as a table tool gave me the same number of results as the combine tool. It's very strange. See EDIT above for a graphic. – user3251223 Sep 10 '14 at 17:07
  • change the analysis extent and that other environment setting (set it to union of inputs) – If you do not know- just GIS Sep 10 '14 at 17:21
  • Hmm ok I basically get what I want when I change the output resolution to be that of layer B (30 m) not of layer A. The result is then ~60,000 records, which makes sense because it is essentially a one to many join. – user3251223 Sep 10 '14 at 17:40