Create a VAT

Summary

A value attribute table (VAT) is built by default for any integer raster that results from an expression, if the range of values (maximum minus minimum) in the raster is less than 100,000 or if the number of unique values in the raster is less than 500.

If the range is less than 100,000, the number of unique values in the raster can be as large as 100,000.

If the range is greater than 100,000, a VAT will still be built if the number of unique values is less than 500.

If the range of values is greater than 100,000 and the number of unique values are greater than 500, then no VAT is automatically built.

At ArcGIS 9.0, the VAT is not created for multitiled rasters. A multitiled raster is usually created when the number of cells times the number of bytes per cell is close to 2 GB. Multitiled raster can be identified by looking in the workspace folder. If there is more than one wNNNNNNx.adf (N = numeric value) file, then the raster is multitiled.

At ArcGIS 9.1, the VAT is created for multitiled rasters.

A bug was introduced, in ArcGIS 9.1, for the BUILDVAT command and a work around is to use
BUILDVAT yourRaster REBUILD_STA

Procedure

• The BUILDVAT command is available in Workstation and from the Raster Calculator in the Spatial Analyst toolbar (available in ArcMap) as well as in the Multi Output Map Algebra tool.
• There is also a script available to do a Build VAT in the Geoprocessing framework of ArcGIS. To download the script, click the link to the BuildVAT Geoprocessing Tool.