The default cell size, or resolution, for analysis results is set to the largest cell size of the input raster datasets for a tool, the Maximum of Inputs.The default cell size when a feature class is used as input to a tool is the width or the height (whichever is shortest) of the extent of the feature class divided by 250.Exercise caution when specifying a cell size finer than the input raster datasets. No new data is created; cells are interpolated using nearest neighbor resampling. The result is as precise as the coarsest input.
Other options available
- Minimum of Inputs sets the cell size of your analysis results to the input raster dataset with the smallest cell size.
- As Specified Below enables you to specify a cell size for analysis results.
- Same as Layer enables you to select an input raster layer on which to base the cell size of your analysis results.
Sometimes you only want to perform analysis on cells in a particular area. The mask identifies those cells within the analysis extent that will be considered when running a tool. If the mask was overlaid on the input raster you want to use for analysis, only cells covered by the mask will be processed. All other cells will be assigned the NoData value in the result after running a tool.
Setting an analysis mask is a two-step process
- The analysis mask must first be created if you do not already have one. An analysis mask can be feature (point, line, or polygon) or raster data. You could create an empty feature class in ArcCatalog, then define the area of interest (the mask) using the ArcMap Editor toolbar. Alternatively, you could create a mask raster using the Reclassify tool, assigning NoData to those cells you want to exclude.
- The analysis mask must then be set on the Environment Settings dialog box.