Available with Image Analyst license.
Computes the differences between two categorical or continuous raster datasets.
This function can be used to enumerate the differences between two classified rasters for land cover change analysis, or it can be used to examine changes between two single-band continuous rasters such as elevation, temperature, canopy cover, and so on.
There are three computation methods:
- Difference—Calculates the mathematical difference (subtraction) between two raster datasets.
To Raster - From Raster
- Relative Difference—Calculates the difference between the raster datasets while accounting for the magnitude of the pixel values.
(To Raster - From Raster)/max(From Raster, To Raster)
- Categorical—The difference between two categorical or thematic rasters, where the output shows every class transition that occurred between the two rasters. For example, a class labeled Forest > Developed indicates a change from Forest in From Raster to Developed in To Raster.
To visualize only the pixels that changed from one class to another, use the From Classes and To Classes parameters, and check the box for Changed Pixels Only. For example, to see only those pixels that changed from Forest to Developed, enter the class value for Forest in the From Class Values, and enter the Developed class value in the To Class Values, then check the box to include changed pixels only. Only the pixels that changed from Forest to Developed will be symbolized in the output layer. All other pixels will be grouped in a class called Other, which is transparent by default.
If Compute Change Method is set to Categorical and one of the inputs is not categorical, a simple difference will be calculated.
When analyzing categorical change, both From Raster and To Raster must have an associated raster attribute table. The attribute table must have either a VALUE field, CLASS_NAME field, CLASSNAME field, or one string field. The data in these fields is used to compare between the two rasters.
If either input is a multiband raster, only the first band in the raster is used for computation.
The first raster to be used in the computation. To evaluate change from time 1 (earlier) to time 2 (later), enter the time 1 raster here.
The second raster to be used in the computation. To evaluate change from time 1 (earlier) to time 2 (later), enter the time 2 raster.
Compute Change Method
The method used for computation.
From Class Values
The class values from the From Raster to be included in the computation, if comparing two categorical rasters. This is a space-delimited list of integer values corresponding to the ClassValue field in your input raster dataset.
To Class Values
The class values from the To Raster to be included in the computation, if comparing two categorical rasters. This is a space-delimited list of integer values corresponding to the ClassValue field in your input raster dataset.
Choose the filter method for categorical change computation.
Use Color Method
Specify the method to use for symbolizing the pixels that have changed classes.
Choose which cell size to use in the output raster. If all the input cell sizes are the same, all the options will yield the same results.
Choose which extent should be used in the output raster: