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I want to extract the raster cells from a big raster with the raster cells from a smaller raster which is overlapping with the bigger raster. Unfortunately, I cannot find a tool for that in ArcMap 10.3.1, but is there a way to do it? I do not want to subtract the values, but there should be noData in the new bigger raster where the bigger raster is overlapping with the smaller raster, like a hole in the bigger raster with the extent of the smaller one.

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  • Con(is null(small),big) in raster calculator. – FelixIP Sep 28 '16 at 18:47
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Use a conditional statement in the raster calculator.

See the ArcGIS documentation on:

EDIT
You can set the output in the area of the smaller raster to something like 9999 and then use the setNull tool, or reclassify to turn it to NoData. Another simple alternative, if the 'smaller' raster has the same extent as the bigger one, is to use the reclassify tool to make the black area (persumably currently set to a value of 0) to NoData and the NoData areas to 1. Then simple multiply the result of that operation with 'bigger'.

  • Thank you. This is the solution at the moment: `Con(IsNull("smaller"),"bigger","bigger" == "smaller") I reclassified the smaller raster to raster value 0 before running the raster calculator but I could not find a solution to get noData for the smaller raster extension in the bigger raster. Does someone have an advice? – nora Sep 28 '16 at 12:48
  • Okay, I really need to put the values from the smaller raster into noData. Having them only set to 0 is not enough because there are also other raster cells with the value 0 and I need them for my statistic. It would be wonderful if someone can support me with the raster calculator expression. Thanks! – nora Sep 28 '16 at 13:53
  • The simplest way is to use a second step - see my edits. – MappaGnosis Sep 28 '16 at 14:10
  • I am sorry for asking again, I just didn't get the point how to “set the output in the area of the smaller raster to something like 9999” with the combination of the bigger raster. Sorry, but I haven’t used the tool “CON” before…. Thank you so much – nora Sep 28 '16 at 14:49
  • Try: Con(smaller = 0, NoData, bigger). assuming that the black area of smaller is zero (based on your comments). I don't have ArcGIS to hand and its been a while so I can't remember if it will take the NoData entry. If that fails then do it in two steps as described above using Con(smaller = 0, -99999, bigger). Then reclassify the result to set -99999 to NoData. To summarize, in the con statement you can either reference a raster to give the output value or you can specify a number for the true or false values in the con statement. – MappaGnosis Sep 28 '16 at 15:06

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