On 11-03-21 08:28 AM, Tom Jeffery wrote:
What is the proper way to extract all the unique values contained in a raster
Band object? I had initially assumed that if a RasterAttributeTable object
existed, it would contain a "Value" column, but I have come across instances
where the only column in the table is a "Histogram" field containing the counts
of each pixel value, but not the value itself.
Currently, I check for the existence of the table, check to see if it has a
Value column, and if not, inspect each pixel value to get the unique set. The
pixel scanning fallback method is quite slow, however, and when I view the same
rasters in ArcCatalog and bring up the "Table" view, it is able to instantly
display the typical Value / Count table. Is there some trick I'm missing here
on how to get these values?
Tom,
I believe that ArcGIS is using the GetHistogram() method on the band which
can also find the histogram stored in other ways than a RasterAttributeTable.
Best regards,
--
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I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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