Update Accuracy Assessment Points—Help

Available with Spatial Analyst license.

Summary

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

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

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.

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

Parameter	Explanation	Data Type
in_class_data	Input classification image or other thematic GIS data reference data. The input can be a raster or feature class. Typical data is a classification image (single band, integer data type) or the training polygon output from an ArcMap image classification toolbar. 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)	Choose whether your input data is a classified image or ground truth data. CLASSIFIED —Select this option if your input is a classified image. This is the default. GROUND_TRUTH —Select this option if your input is reference data.	String

This example updates the points used for accuracy assessment.

import arcpy
from arcpy.sa import *

arcpy.gp.UpdateAccuracyAssessmentPoints("aapnt1.shp", "grndtru.tif", "aapnt2.shp", "GROUND_TRUTH")