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I'm using ArcGIS 10.3 and want to look at elevation vs frequency of each elevation for a DEM. There seems to be two ways to create this graph:

  1. Use the "Create histogram" tool on the Spatial Analyst toolbar.
  2. Go to View>Graphs>Create Graph.

The Histogram graph type in Create Graph looks very different to the Spatial Analyst one and I can't find a way to even set the x-axis field, so the graph doesn't work. The Vertical Bar graph type seems to be what I need but there are some differences that I don't understand. The graph created through the Spatial Analyst toolbar has a frequency count maximum of about 11,000. The Vertical Bar graph has a frequency count maximum of about 220,000. And although the general pattern of frequencies is the same, there are some differences - e.g. a couple of spikes are massive on the Vertical Bar graph compared the the Spatial Analyst histogram.

I can't find any ArcGIS documentation that explains this. Can anyone help?

Edit: By the way I am zoomed to the full extent of the DEM, so the Spatial Analyst histogram includes all pixels.

  • I would suggest you search the help file for "spatial analyst toolbar" it explains various things about the histogram button on the toolbar, for example it honours selections, this could account for your differences? It may also be sub-sampling, I don't know, but that's the sort of thing you could possibly tweak in the properties of the graph. – Hornbydd Sep 13 '15 at 17:10

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