Available with Image Analyst license.
Summary
Generates a raster containing pixel change information using the output change analysis raster from the Analyze Changes Using CCDC tool.
Usage
This tool uses the output change analysis raster generated from the Analyze Changes Using CCDC tool to generate a raster containing pixel change information. The change analysis raster contains information about how each pixel has changed over time. Harmonic regression is used to fit the pixel value's changes to a curve, and large changes in that curve are considered potential land use or land cover changes.
The Change Type parameter indicates the information that will be generated. Information is extracted from the change analysis raster. There are four options:
- Time of latest change—The most recent date and time at which a pixel was flagged as being changed
- Time of earliest change—The earliest date and time at which a pixel was flagged as being changed
- Time of largest change—The date and time at which the calculated change was the most significant for a pixel
- Number of changes—The total number of times the pixel changed
The output raster is a multiband raster in which each band contains change information depending on the change type selected and the maximum number of changes specified. For example, if the Change Type parameter is set to Time of earliest change and the Maximum Number of Changes parameter is set to 2, the tool calculates the two earliest dates when change occurred throughout the time series for every pixel. The result is a raster in which the first band contains the dates of the earliest change per pixel, and the second band contains the dates of the second-earliest change per pixel.
Syntax
DetectChangeUsingChangeAnalysisRaster(in_change_analysis_raster, {change_type}, {max_number_changes})| Parameter | Explanation | Data Type |
in_change_analysis_raster | The multidimensional change analysis raster generated from the Analyze Changes Using CCDCtool. Currently, only a change analysis raster in Cloud Raster Format (.crf) is supported. | Raster Dataset; Raster Layer; Image Service |
change_type (Optional) | Specifies the change information to calculate for each pixel.
| String |
max_number_changes (Optional) | The maximum number of changes per pixel that will be calculated when the change_type parameter is set to TIME_OF_LATEST_CHANGE, TIME_OF_EARLIEST_CHANGE, or TIME_OF_LARGEST_CHANGE. This number corresponds to the number of bands in the output raster. The default is 1, meaning only one change date will be calculated, and the output raster will contain only one band. | Long |
Return Value
| Name | Explanation | Data Type |
| out_raster | The output raster containing the detected change information. | Raster |
Code sample
This example returns the most recent date at which pixels changed in a NDVI time series.
# Import system modules
import arcpy
from arcpy.ia import *
# Check out the ArcGIS Image Analyst extension license
arcpy.CheckOutExtension("ImageAnalyst")
# Execute
dateOfLatestChange = arcpy.ia.DetectChangeUsingChangeAnalysis(
"Monthly_NDVI_Change_Analysis.crf", "TIME_OF_LATEST_CHANGE", 1)
# Save output
dateOfLatestChange.save(r"C:\data\NDVI_LatestChanges.crf")This example returns the total number of times the pixels changed in a Landsat time series.
# Import system modules
import arcpy
from arcpy.ia import *
# Check out the ArcGIS Image Analyst extension license
arcpy.CheckOutExtension("ImageAnalyst")
# Define input parameters
in_change_analysis = r"C:\data\Landsat_ChangeAnalysis.crf"
change_type = "NUM_OF_CHANGES"
# Execute
number_of_changes = arcpy.ia.DetectChangeUsingChangeAnalysis(
in_change_analysis, change_type)
# Save output
number_of_changes.save("C:/data/NumberOfChanges_Landsat.crf")Environments
Licensing information
- Basic: Requires Image Analyst
- Standard: Requires Image Analyst
- Advanced: Requires Image Analyst