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Update Accuracy Assessment Points

Available with Spatial Analyst license.

Available with Image Analyst license.

Summary

Updates the Target field in the attribute table to compare reference points to the classified image.

Accuracy assessment takes known points and uses them to assess the validity of the classification model.

Usage

  • Update the attribute table of a feature class that represents accuracy assessment points. If you created the feature class using the Create Accuracy Assessment Points tool, there will be a field for GROUND_TRUTH and for CLASSIFIED. This tool can start with either reference data and compare it to the classified output, or it can start with the classified output and compare that to reference data.

    These two fields are then compared using the Compute Confusion Matrix geoprocessing tool.

  • You can manually update the GROUND_TRUTH field if you want to change or identify a set of points.

Syntax

UpdateAccuracyAssessmentPoints(in_class_data, in_points, out_points, {target_field})
ParameterExplanationData Type
in_class_data

The input classification image or other thematic GIS reference data. The input can be a raster or feature class.

Typical data is a classification image of a single band, integer data type.

If using polygons as input, only use those that are not used as training samples. You can also use land-cover data in shapefile or feature class format.

Raster Layer; Mosaic Layer; Feature Layer
in_points

The point feature class providing the accuracy assessment points to be updated.

All points from this input will be copied to the updated output feature class, and the target_field will be updated from the input raster or feature class data.

Feature Layer
out_points

The output point feature class which contains the updated random point field for accuracy assessment purposes.

Feature Class
target_field
(Optional)

Specifies whether your input data is a classified image or ground truth data.

  • CLASSIFIEDThe input is a classified image. This is the default.
  • GROUND_TRUTHThe input is reference data.
String

Code sample

UpdateAccuracyAssessment example 1 (stand-alone script)

This example updates the points used for accuracy assessment.

import arcpy
from arcpy.ia import *

# Check out the ArcGIS Image Analyst extension license
arcpy.CheckOutExtension("ImageAnalyst")

UpdateAccuracyAssessmentPoints("c:\\test\\aapnt1.shp", "c:\\test\\grndtru.tif", "c:\\test\\aapnt2.shp", "GROUND_TRUTH")

Environments

This tool does not use any geoprocessing environments.

Licensing information

  • Basic: Requires Image Analyst or Spatial Analyst
  • Standard: Requires Image Analyst or Spatial Analyst
  • Advanced: Requires Image Analyst or Spatial Analyst

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