Error: Grid Has No VAT or an Error Message is Returned When Opening or Reading VAT

Error Message

In ArcGIS Spatial Analyst, Zonal Statistics on a feature Zone input may generate an error if the extent of the feature data is within a cell of the Value raster input.

If the Zone item is an integer, an error message similar to the following may occur:

  Executing (ZonalStatistics_1): ZonalStatistics zone_shp
  item_int val_grd E:\data\zstat_max MAXIMUM DATA
  An error was encountered while executing ZonalStatistics.
  ("esriGeoAnalyst.GridEngine") Grid has no VAT
  Failed to execute (ZonalStatistics_1).

If the Zone item is text, an error message similar to the following may occur:

  Executing (ZonalStatistics_2): ZonalStatistics zone_shp 
  item_text val_grd E:\data\zstat_max MAXIMUM DATA
  An error was encountered while executing ZonalStatistics.
  ("esriGeoAnalyst.GridEngine") Error in opening or reading VAT
  Failed to execute (ZonalStatistics_2)./PRE}

Cause

With default tool behavior, this type of input does not suit analysis with a Zonal operation.

If the entire zonal input dataset falls within one cell of the Value raster, then determining statistics for that zone, such as maximum or variety, would be meaningless.

To demonstrate this, consider a case where the cell size of the 4 by 4 cell zone input is 1, and the value input is one cell of resolution 6. Resampling the value input to that of the zone input results in a 6 by 6 cell raster with each cell having the same value, as demonstrated here:

    Zone input:       Value input: 
                      9 9 9 9 9 9 
       1 1 2 2        9 9 9 9 9 9 
       1 1 2 2        9 9 9 9 9 9 
       3 3 4 4        9 9 9 9 9 9 
       3 3 4 4        9 9 9 9 9 9 
                      9 9 9 9 9 9

The following are the outputs for several Zonal statistics:

    Zonal Majority:  Zonal Maximum:   Zonal Variety:
     ~ ~ ~ ~ ~ ~      ~ ~ ~ ~ ~ ~      ~ ~ ~ ~ ~ ~ 
     ~ 9 9 9 9 ~      ~ 9 9 9 9 ~      ~ 1 1 1 1 ~ 
     ~ 9 9 9 9 ~      ~ 9 9 9 9 ~      ~ 1 1 1 1 ~ 
     ~ 9 9 9 9 ~      ~ 9 9 9 9 ~      ~ 1 1 1 1 ~ 
     ~ 9 9 9 9 ~      ~ 9 9 9 9 ~      ~ 1 1 1 1 ~ 
     ~ ~ ~ ~ ~ ~      ~ ~ ~ ~ ~ ~      ~ ~ ~ ~ ~ ~

Note:
 '~' represents NoData

There is no variation in the output raster cell values.

Feature inputs are converted to rasters internally. More information is available in the Tool Reference help, as well as at the following:
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/25176' target='_blank'>How To: Set the Environment settings for Zonal Statistics when using a feature layer as the zone layer</a>

Solution or Workaround

Reconsider what is being determined with the Zonal operation. In particular, the extent of the Zone input should exceed that of any single cell in the Value raster.

One way to accomplish this is by using a value raster with a higher resolution.

Another way to accomplish this is to set the analysis cell size to MinOf (instead of the default MaxOf) or to the size of the zone input.

Article ID:000008520

Software:

ArcMap 9 x

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Grid has no VAT or an error message is returned when opening or reading VAT

Error Message

Cause

Solution or Workaround

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