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Bug: SAMPLE Tool appears to hang with certain floating point rasters

Description

The SAMPLE Tool appears to hang with certain floating point rasters. A large temporary scratch file is written and this file continues to grow in size.

This has been resolved in ArcGIS 9.1

Cause

This is a known issue.

Workaround

Follow the steps below.

  1. Multiply the floating point raster by a factor, and then convert it to integer. When the SAMPLE operation is performed, the resulting values must be divided by this factor to return to the initial range.

    The multiplication factor is determined by how much precision is required to maintain. If the range of values in the rasters are, for example, 124.547857 to 23,577.937356, and only one decimal place is needed, use 10 as the factor. Performing SAMPLE on this dataset results in a table with values in a potential range of 1,245 to 235,779. The values in the table can then be divided by the factor to return to the same potential range as the original values, 124.5 to 23,577.9. In another case, the input values range from 0.113445 to 1.945679 and four significant digits are required, so use a factor of 10,000 to get a value range of 1,134.45 19,456.79 before performing the INTEGER operation.
  2. Apply the multiplication factor to the raster with the Math TIMES tool, or with the the Raster Calculator.

    For example:
    ' Int( myGrid * 10000) '

  3. Run the SAMPLE tool

    For example:
    Output table is 'Sample_myGrid.dbf'

  4. Run the CALCULATE FIELD Tool under Data Management/Fields to divide the attribute value by the multiplication factor.

    For example:
    Input table is 'Sample_myGrid.dbf', Fieldname is 'myGrid', Expression is '[myGrid] / 10000'