Available with Spatial Analyst license.
Records, for each cell in the output, the identity of the connected region to which that cell belongs. A unique number is assigned to each region.
This is a global raster function.
In general, the first region scanned receives the value one, the second two, and so on, until all regions are assigned a value. The scan moves from left to right, top to bottom. The values assigned to the output zones are based on when they are encountered in the scanning process.
There are two parameters that control how connectivity between regions is established. The Number of Neighbor Cells parameter determines the geometry of the connectivity, either as orthogonal (four way) only, or as diagonal as well as orthogonal (eight way). The Zone Connectivity parameter determines which cell values are considered when evaluating connectivity.
By default, the Add Link parameter setting is enabled. This will create a LINK field in the attribute table of the output raster, which retains the original zone value for each cell from the input raster. This parameter only applies when the Zone Connectivity parameter is set to Within. If it is set to Cross, the attribute table of the output raster will only contain the usual Value and Count fields.
When available, the LINK field allows you to trace the parentage of each newly created region back to the original input zone values, to be used for additional analysis.
Cell locations that contain the excluded value receive zero on the output so that these zones are not confused with existing NoData cell locations. Since the numbering begins with the value 1, the cells that are excluded from the regroup are considered background. These background cells can be reclassed or manipulated in the same way as any other value.
The input raster for which unique connected regions of cells will be identified.
It must be of integer type.
Number of Neighbor Cells
Specifies the number of neighboring cells to use when evaluating connectivity between cells that define a region.
Defines which cell values should be considered when testing for connectivity.
Specifies whether a link field will be added to the table of the output when the Zone Connectivity parameter is set to Within. It is ignored if that parameter is set to Cross.
A value that excludes all cells of that zone value from the connectivity evaluation. If a cell location contains the value, no spatial connectivity will be evaluated, regardless of how the number of neighbors is specified.
Cells with the excluded value will be treated in a similar way to NoData cells, and are eliminated from consideration in the operation. Input cells that contain the excluded value will receive 0 on the output raster. The excluded value is similar to the concept of a background value.
If a zone in the input raster has a value of 0, to have that zone be included in the operation, specify a value for this parameter that is not present in the input. For example, if an input raster has values of 0, 1, 2, and 3, specify an Excluded Value of 99. Otherwise, all cells of value 0 in the input will be 0 in the output, and will also not have their individual regions determined.