trudnick

Help needed getting majority aspect for parcel fc when using 32-bit raster.

Discussion created by trudnick on Jul 10, 2012
Latest reply on Jul 10, 2012 by trudnick
I have the steps to a process created years back with Workstation & coverages.   For obvious reasons, this process must be brought into this century in order to be used going forward.

This seems somewhat simple.  I have a feature class which was created by doing IDENTITY of parcels and buildings (buffered to 150').  The results of the IDENTITY need to be overlaid with an ASPECT raster to determine the majority aspect of the area within the building buffers.  I know I should be able to do this by running ZonalStatisticsAsTable.  I have already done something similar using the parcels and the SLOPE raster, resulting in the average slope % for each parcel. 

The problem comes when trying to use ZonalStatisticsAsTable to overlay the ASPECT with the parcel/building feature class.  When the dialog appears and the raster is added as the 'input value raster' argument, there is suddenly no value called 'Majority' in the 'Statistics type' dropdown list.  I have to assume this is because the ASPECT raster needs an attribute table, so I try to build one on my 1-band ASPECT raster.  No good.  You cannot build an attribute table for a raster if you have 32 bit data, which is what I have because the original DEM data used to create the ASPECT is 32-bit. 

Are there any solutions for this?  I thought of downscaling the ASPECT to a 16-bit raster, but don't see any likely tools in ArcCatalog to do this - I assume it would have to be done by the originator of the DEM data (it was not produced in-house)?

Any thoughts on how I might work this process out would be very welcome, I seem to be stuck at this point.  If this needs to be in a different Forum, please let me know.  I figure I can either get suggestions on a different way to get the parcel Aspect through geoprocessing or get the raster itself changed to work with the tools.

Thanks
Tami

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