Environment settings for raster data

Environment settings include the general settings for parameters, such as the default workspace or output coordinate system, and specific settings for other data types or applications. Environment settings can be set at three levels: for the application you are working in so they apply to all tools, for a model so they apply to all processes within the model, or for a particular process within a model. You can set these before you begin using a tool or while setting up the parameters for the tool.

To learn more about environment settings, see What is a geoprocessing environment.

Raster-specific environment settings	Description
Output extents
Snap Raster	A snap raster can be used to ensure that the cell alignment of output rasters matches to an existing raster. The lower left corner of the extent is snapped to a cell corner of the snap raster, then the upper right corner is adjusted using the output cell size. As a result, when the output cell size is the same as the snap raster cell size, the cells in the output raster are aligned with the cells of the snap raster.
Raster analysis
Cell size	You can specify the output cell size or resolution, or you can take the default. The default cell size, or resolution, for analysis results is set to the largest cell size of all the input raster datasets for the tool. The default output resolution, when a feature class is used as input, is the width or height (whichever is shorter) of the extent of the feature class divided by 250.
Mask	A mask identifies those cells within the analysis extent that will be considered when performing an operation or a function. Setting an analysis mask means that processing will only occur on selected cells and that all other cells will be assigned values of NoData.
Raster storage
Pyramid	Pyramids are reduced-resolution representations of your dataset. They can speed up display of raster datasets by retrieving only the data that is necessary at a specified resolution. By default, pyramids are created for raster datasets. There are many options to control the number of levels of pyramids, if they will be compressed, and what resampling techniques will be used.
Raster Statistics	Statistics are required for your raster dataset to perform certain tasks, such as applying a contrast stretch or classifying your data. It is not essential to build statistics if they have not already been calculated, since they are calculated the first time they are needed. It is recommended that you calculate statistics for your raster datasets before using them if you want to use certain features that require statistics. In most cases, the default display of your raster will be improved if statistics have already been calculated, because a standard deviation stretch is applied if statistics are present. Setting a skip factor allows you to speed up the process of calculating statistics by skipping pixels.
Compression	The Compression type is used by any tools that load or store raster data in blocks. The primary benefits of compressing data are that compressed data requires less storage space and data display times will be quicker, as there is less information to transmit. The main differences in the compression types are if they are lossy or lossless. Lossless compression preserves all raster cell values, whereas raster cell values may not be preserved after compression and decompression with lossy compression.
Tile Size	The tile size setting is used by any tool that creates raster datasets in blocks. These raster datasets are stored as a binary large object (BLOB) data type. The tile size option lets you control the number of pixels that are stored in each BLOB and, therefore, lets you control the size of each BLOB. It is specified as the number of pixels in x (tile width) and y (tile height). The default tile size is 128 x 128, which is good for most cases. However, if the tile size is too big, you will end up bringing up more data than is needed each time you access the data.

List of the environment settings for raster data