Error: ("esriGeoAnalyst.GridEngine") Field not found. Invalid field index obtained
** This error has been fixed at ArcGIS Desktop 9.1 **
When a string field is used in the Spatial Analyst Reclassify tool and set as the Old Values column, a string field is added to the raster output from Reclassify. The strings in the rows of this output string field are created by grouping the characters from the list of attributes in the Old Values column, that is, all the attributes mapped to the same new value.
Since there is a limit of 256 characters on the length of a string field, reclassify fails to run if this limit is reached when processing and displays the following error message:
"("esriGeoAnalyst.GridEngine") Field not found. Invalid field index obtained."
The limit on the length of a string field of 256 characters has been reached.
For example, with the following remap table:
Old value New value
The output raster's string field has a width of 26 characters. The characters and the counts are listed below:
"Value1" = 6
"Value2" = 6
"Valueabc" = 8
"Value4" = 6
"Value1"+"Value2"+"Valueabc"+"Value4" = 6 + 6 + 8 + 6 = 26
Since this is below the limit of 256 characters, reclassify works fine.
Solution or Workaround
There are several workarounds:
- Workaround 1
1. Add a new string field prior to reclassifying.
2. Type in a short code representing each attribute.
- Workaround 2
1. Add a new string field.
2. Start an edit session.
3. Calculate the values of this new field as a reduced version of the string field. Right-click the field name in the attribute table and click Field Calculator.
([new_stringField] = Left([stringField], 3)
The number 3 represents the number of characters to take, starting from the left. Depending on how many attributes are in the string field, specify a lower number or use a higher number. Ultimately, the string field in the output raster must be less than 256 characters in length.
- Workaround 3
If string attributes are not needed in the output reclassified raster, use 'value' as the field to use in reclassify, instead of a string field.
- Workaround 4
Reduce the number of attributes in the string field before reclassifying.