Environment settings are additional parameters that affect the results of analysis and how the analysis is run. Environment settings can be applied to the web map by clicking Analysis settings in the Analysis pane, or to an individual tool using the Environment settings parameter group in the tool pane.
When you set analysis environment settings in the web map, any new tool that is opened will inherit the map level environment settings. Only certain environment parameters will be used by a given tool. To determine the environments that a tool will use, consult the environment section of the tool's reference page. You can set environments individually for any tool that you open in the tool pane, under the Environment settings parameter group. These settings will only be used until the tool is closed, and will not be saved if the tool is opened again. If you reopen a tool from History, it will repopulate with the environments that were used when it was previously run.
Output coordinate system
Output coordinate system specifies the coordinate system for analysis and the result layer. The following options are available:
- Same as input (default)—The result of your analysis will be in the same coordinate system as the input.
- Choose coordinate system—The result of your analysis will be in the coordinate system you choose. Click the Browse coordinate systems button to choose from a list of coordinate systems.
- Same as layer—The result of your analysis will be in the same coordinate system as an existing layer on the web map. Click the Layer button to choose from a list of layers.
If Same as layer is specified and the chosen layer has a coordinate system defined by a Well-Known Text (WKT) string, the coordinate system will not populate in the parameter and it will not be used in analysis.
Processing extent specifies the extent or boundary when the analysis is run. All input features or cells that are completely within or that intersect the specified extent are used in the analysis. The following options are available:
- Full extent (default)—The extent provided by the tool.
- Coordinates—The extent is defined by the coordinates you provide to create a bounding rectangle. Click the Set coordinates from current display extent button to populate the coordinates based on the current map extent.
- Display extent—The extent is defined by the visible extent of the web map at the time when the Run button is clicked.
- Layer—The extent is defined by the spatial extent of an existing layer on the web map. Click the Layer button to choose from a list of layers.
Snap raster adjusts the extent of the output raster layer so it matches the cell alignment of the specified Snap raster layer for raster analysis. Click the Layer button to choose from a list of layers.
Cell size specifies the cell size or resolution that is used to create the output raster layer in raster analysis. The following options are available:
- Maximum of inputs (default)—The cell size is defined by the largest cell size of all input layers.
- Minimum of inputs—The cell size is defined by the smallest cell size of all input layers.
- As specified—The cell size is defined using a custom number value.
- From layer—The cell size is defined by the cell size of an existing layer on the web map. Click the Layer button to choose from a list of layers.
Mask specifies a raster layer or feature layer that is used to define your area of interest for raster analysis. Only those cells that fall within the analysis mask are considered in the analysis operation. Click the Layer button to choose from a list of layers.
If the analysis mask is a raster, all cells that have a value will define the mask. Cells in a mask raster that are NoData are considered to be outside the mask and will be NoData in the analysis result layer.
If the analysis mask is a feature layer, it will be internally converted to a raster when the analysis is run. For this reason, ensure that Cell size and Snap raster are set appropriately for your analysis.
Resampling method specifies how to interpolate pixel values when transforming your raster dataset. This environment is used for raster analysis when the input and output do not line up, when the pixel size changes, when the data is shifted, or a combination of these situations. The following options are available:
- Nearest neighbor—Used primarily for discrete data, such as a land-use classification, since it does not create new pixel values. This method is also appropriate for continuous data when you want to preserve the original reflectance values in imagery for accurate multispectral analysis. It is the most efficient in terms of processing time but may introduce small positional errors in the output image. The output image may be offset by up to half a pixel, which may cause the image to have discontinuities and a jagged appearance.
- Bilinear interpolation—This method is most appropriate for continuous data. It performs a bilinear interpolation and determines the new value of a cell based on a weighted distance average of the four nearest input cell centers. It creates an output image that is smoother in appearance than Nearest neighborhood but alters the reflectance values, which results in blurring or loss of image resolution.
- Cubic convolution—Suitable for continuous data. This method performs a cubic convolution and determines the new value of a cell based on fitting a smooth curve through the 16 nearest input cell centers. The result is geometrically less distorted than the raster achieved with Nearest neighbor and sharper than Bilinear interpolation. In some cases, it can result in output pixel values outside the range of input cell values. If this is unacceptable, use the Bilinear interpolation method instead. Cubic convolution is computationally intensive and takes longer to process.
Specify the processor type used to run the analysis.
The following options are available:
- Automatic—The tool defines the processor type with no restrictions. This is the default.
- CPU—Processing will use the CPU. CPU processing can be parallelized across multiple cores and instances, as handled by the Parallel processing factor.
- GPU—Processing will use the GPU. GPUs are effective at graphics and image processing, where their highly parallel structure makes them efficient in processing large blocks of data in a repetitive manner. The raster analysis tools that honor this environment can distribute its job across GPU instances at multiple raster analysis server machines, as handled by the Parallel processing factor.
Parallel processing factor
Specify the number of raster processing service instances that can be used for processing your data.
If the tool doesn't honor the Processor type environment, or if the Processor type environment is set to CPU, the Parallel processing factor environment controls raster processing (CPU) service instances. If the Processor type environment is set to GPU, the Parallel processing factor environment controls the number of raster processing GPU instances.
By setting the Parallel processing factor environment, you can request the number of parallel workers that the raster analytics image server uses to process one raster analysis task. However, if the total number of parallel processes exceeds the maximum number of raster processing (CPU or GPU) service instances, the additional parallel processes will be queued.
- Empty string—The tool will use 80 percent of the maximum number of raster processing service instances. This is the default.
- Whole number—The operation will be spread across the specified number of raster processing service instances. Accepted values include 0 and positive integers.
- Percentage—The operation will be spread across the specified percentage of available raster processing service instances. Percentages must include a percent sign (%) following the percentage value (for example, 50%).