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Raster Tools Aggregate
This tool is used to generate reduced-resolution versions of rasters, that is, from small to larger pixels. Each output cell contains the Sum, Minimum, Maximum, Mean, or Median of the input cells that are encompassed by the extent of that cell. The tool uses the standard ArcGIS ‘Aggregate (Spatial Analysis)’ tool. For more detailed help see ESRI Help for the ‘Aggregate (Spatial Analyst)’ tool.
Table for Rasters: This is the input table, usually the results table generated by the Geodata > Search tool, but it can be any table with a field containing the full path to the rasters you want to clip. If the Input Table is a DBF, or a table in an ESRI File Geodatabase, then you can select a subset of rows in ArcMap and only those rows will be processed by the tool.
Field for Raster: Select the field from the 'Table for Rasters' that contains the full path to the raster items you want to aggregate.
Cell Aggregation Factor: The factor by which to multiply the cell size of the input raster to obtain the desired resolution for the output raster. For example, a cell factor value of three would result in an output cell size three times larger than that of the input raster. The value must be an integer greater than 1.
Format for output rasters: Raster format for output geodata. You can choose from: Esri Grid, img (ERDAS IMAGINE) or tif (GeoTIFF). If you select a file geodatabase for the Result Workspace then the output format will default to ‘Esri Grid’.When storing your raster geodata to a JPEG file, a JPEG 2000 file, a TIFF file, or a geodatabase, you can specify a compression type and compression quality within the ‘Environment Settings’. Select from:
- Esri Grid
- tif (GeoTiff file)
- img (Image file)
Output Workspace: This is the location for the Grid Garage results table containing the list of geodata processed by the tool as well as any data outputs. If the tool encounters any errors when processing the input geodata then a second results table will be generated, with a ‘_FAIL’ suffix, listing the input geodata that failed and any ESRI error messages.
If you have set the ArcGIS ‘Workspace' parameter in the Geoprocessing > Environment Settings then this path will be used as the default. You can use this default path or click the folder button to select a new output location which can be a folder or File Geodatabase. If you specify a folder then the Results Table will be written to a comma-delimited (CSV) text file, if you specify a File Geodatabase it will be written as a Geodatabase Table.
Result Table Name: You can choose to use the default table name or specify a different name for the Grid Garage results table. The Grid Garage results table reports on a range of different properties for each of the geodata items in the 'Table for Geodata' input table. See the Grid Garage User Manual for a description of all the properties reported on.
If the tool encounters any errors when processing any of the geodata then a second results table will be generated, with a ‘_FAIL’ suffix, listing the input geodata that failed and any ESRI error messages. If you choose a folder for the Output Workspace then the result table will be written to a comma-delimited (CSV) text file which will not allow you to select rows for processing when using the table as input for other Grid Garage Tools.
Result Table file name: The default name will always take the form of ‘AggregateRasterTool_date_time’, where ‘date’ and ‘time’ are the date and time that the tool was run.
Aggregation Method (optional): Establishes how the value for each output cell will be determined. The values of the input cells encompassed by the coarser output cell are aggregated by one of the following statistics:
- SUM — The sum (total) of the input cell values. 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.
Extent Boundary (optional): Defines how to handle the boundaries of the input raster when its rows or columns are not a multiple of the cell factor. Select from:
- EXPAND — Expands the bottom or right boundaries of the input raster so the total number of cells in a row or column is a multiple of the cell factor. Expanded cells are given a value of NoData. With this option, the output raster can cover a larger spatial extent than the input raster. This is the default. This is the default.
- TRUNCATE — Reduces the number of rows or columns in the output raster by 1. This will truncate the remaining cells on the bottom 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.
If the number of rows and columns in the input raster is a multiple of the cell_factor, these keywords are not used.
NoData Treatment (optional): Denotes whether NoData values are ignored by the aggregation calculation. Select from:
- DATA — 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.
- NODATA — 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 the NODATA keyword 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.
Output File Workspace (optional): If you want the output geodata files to be saved in a different location to the ‘Output Workspace’ you can select a new location (folder or File Geodatabase, depending on the output file type). The result tables will still be written to the ‘Output Workspace’ specified above.
Output Filename Prefix (optional): Any text you enter in this input box will be added as a prefix (at the beginning) for all output file names.
Output Filename Suffix (optional): Any text you enter in this input box will be added as a suffix (at the end) for all output file names.