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My starting point is a series of bounding box polygons, representing the extents of all the data sets in my inventory.

I am trying to produce an output grid showing the frequency of coverage over the the extent of the entire inventory, in my case the world.

I had thought that a combination of Intersect and Dissolve functions would get me what I wanted, but haven't had any success with this approach yet.

Can anyone suggest a better process? I am open to any suggestions, whether it be some tools already available in ArcMap, QGIS...etc or through programmatic/scripting using ArcPy,GDAL...etc.

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Can you describe in more detail what the output grid should be? When I think grid, I think of a raster, but maybe you are thinking of something else. – blah238 Apr 25 '12 at 5:51
up vote 5 down vote accepted

One simple way to do this would be to create a fishnet polygon layer using Create Fishnet from the same extents as your bounding box layer, and divide it into an appropriate number of columns/rows.

Then perform a Spatial Join with the target layer being the fishnet polygons and the join layer being your bounding box polygons. Do a one to one join; this creates a JOIN_COUNT field with the number of bounding box features that intersect each fishnet polygon.

Symbolize the output by JOIN_COUNT and you have a quick and dirty heat map:

Fishnet Heat Map

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This is exactly what I was looking for. Thank you. – user890 Apr 25 '12 at 11:13

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