I have a lidar DEM model of the Houston area floodplain with polygons representing areas protected by levees. I would like analyze the elevation within each levee by sampling the elevation values within the polygons and representing them as a histogram or frequency plot. Ideally, the x axis would be binned elevation and the y axis would be the frequency (count).
I've tried the Sample Tool from the spatial analyst toolset, but instead of obtaining the elevation values, I seem to be getting a number between 1 and 256 (...the display value?)
are you sure it was the dem values that were being sampled and not a reclassed version of it?
Check... this link ...to see the format of the table you should have received
Thanks for responding. Actually I did try Sample.... but but I'm wanting to compile All of the elevation points within a polygon. What I'm trying to do is to represent the dem elevation values within a polygon in 2-dimensions. Sample is fine for points but I'm looking to represent area in an "elevation histogram" or frequency plot. Any suggestions on what tool to use for this?
oh.. I normally extract the area of the raster that I am interested in, convert it to a numpy array (RasterToNumPyArray in arcpy.da module), then use python/numpy and matplotlib to do graphing. Their graphing tools and handling of raster data for graphing purposes is much easier to use (example of producing a histogram here )
Thanks, Python and Matlab are both tools that I would like to learn someday.
Could you include a sreenshot of the raster in the TOC? If the data is stored in a Mosaic dataset and if it has a certain renderer defined by default (raster function) you may be looking at the values of the 1st band of the visualization and not the actual elevation values.
Is this helpful?
Yes it is, but can you expand the "Statistics"part?
No statistics have been calculated... do I need to do this?
if you want to see the statistics, you can either calculate them when you bring them in or afterwards using