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I am trying to erase a raster and is there a erase command for the Raster side? I am using ArcGIS 9.3.1. I have 2 rasters that are in the Landcover and there is overlap in between and would like to remove the overlap and then merge them later.

Thanks, Robert

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What format are your two rasters in? – Mapperz♦ Apr 13 '11 at 17:54
They are both in img files but they were saved from ArcGIS and not from ERDAS. – PROBERT Apr 13 '11 at 18:33

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There is no erase tool for rasters that I know of. This may not be the most efficient way to go about it, but I would use the "extract by mask" function thusly:

  1. make polygons of the extents of each of the two rasters
  2. erase the overlapping portion of the one polygon
  3. use this polygon to do an extract by mask

There may be a shorter way to do this, but this is just the first thing that comes to mind.

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The "erase" command is called setnull. – whuber♦ Apr 13 '11 at 19:54
how would you create the extent polygon for a raster which includes a nodata collar? (e.g. the image is rotated and a straight min/max of extent coordindates is inappropriate). – matt wilkie♦ Jun 30 '11 at 0:05
up vote 3 down vote

The Mosaic Tool in ArcMap provides options for mosaicing raster data which can contain overlaps. The version 10 help file is shown, previous versions are the same.

Edit

See Mapperz link for 9.3 and before someone asks, here is the link for ArcMap 9.2

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Thanks, but don't have that ArcGIS 10 version yet. I'll stick-note my mind ha ha – PROBERT Apr 13 '11 at 18:51
It's is in ArcGIS 9.3 - webhelp.esri.com/arcgisdesktop/9.3/… – Mapperz♦ Apr 13 '11 at 19:45
the mosiac tool doesn't help in the case where you want both of a) smooth blending at the edges of overlap and b) don't want blending of pixel values in the interior of the overlap. One must choose to either blend or have one of the inputs win. – matt wilkie♦ Jun 29 '11 at 23:25
clarification: the 'blend' and 'mean' options for the mosaic use a weighted distance average, so the farther to the interior you go the less effect the other raster has. There is no user control over the wieghts or distance though. – matt wilkie♦ Jun 30 '11 at 15:49

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