Aggregate function

Overview

Generates a reduced-resolution version of a raster.

Notes

Depending on the value provided for the cell factor (whether the division of the cell factor by the number of cells in a row or column leaves a remainder), the spatial extent of the input raster may not cover the same extent for the last cell in a row or column as the output raster. When this occurs, the value for the last output row or column of cells can be calculated with the available cells from the input raster that fall within the extent if the Expand extent if needed parameter is checked. If that parameter is unchecked, the output raster will be truncated by removing the last row or column of cell from the output raster.

For the Aggregation Technique settings of Maximum, Minimum, or Sum, the output raster type will be the same as that of the input raster. If the setting is Mean or Median, the output type will always be float.

Parameters

Parameter	Description
Raster (Required)	The input raster to be aggregated. It can be of integer or floating point type.
Cell Factor	The factor by which the cell size of the input raster will be multiplied. The value must be an integer greater than 1. For example, a cell factor value of 3 results in an output cell size three times larger than that of the input raster.
Aggregation Technique	The method that will be used for aggregation. The values of the input cells encompassed by the coarser output cells are aggregated by one of the following statistics: Sum—The total of the input cells. This is the default. Maximum—The largest value of the input cells. Mean—The average value of the input cells. Median—The median value of the input cells. Minimum—The smallest value of the input cells.
Expand extent if needed	Specifies whether the boundaries of the input raster will be expanded when its rows or columns are not a multiple of the cell factor. Checked—The top or right boundaries of the input raster will be expanded so the total number of cells in a row or column is a multiple of the cell factor. With this option, the output raster can cover a larger spatial extent than the input raster. This is the default. Unchecked—The number of rows or columns will be reduced by 1 in the output raster. This truncates the remaining cells on the top or right boundaries of the input raster, making the number of rows or columns in the input raster a multiple of the cell factor. With this option, the output raster can cover a smaller spatial extent than the input raster.
Ignore NoData in calculations	Specifies whether NoData values will be ignored during the aggregation calculation. Checked—Specifies that if NoData values exist for any of the cells that fall within the spatial extent of a larger cell on the output raster, the NoData values will be ignored when determining the value for output cell locations. Only input cells within the extent of the output cell that have data values will be used in determining the value of the output cell. This is the default. Unchecked—Specifies that if any cell that falls within the spatial extent of a larger cell on the output raster has a value of NoData, the value for that output cell location will be NoData. When this option is used, it is implied that when cells within an aggregation contain the NoData value, there is insufficient information to perform the specified calculations necessary to determine an output value.