Geoprocessing environment settings are additional parameters that affect a tool's results. They differ from normal tool parameters in that they don't appear on a tool's dialog box (with certain exceptions). Rather, they are values you set once using a separate dialog box and are interrogated and used by tools when they are run.
Changing the environment settings is often a prerequisite to performing geoprocessing tasks. For example, you may already be familiar with the Current and Scratch workspace environment settings, which allow you to set workspaces for inputs and outputs. Another example is the Extent environment setting, which allows your analysis to be limited to a specific geographic area, or the Output Coordinate System environment setting, which defines the coordinate system (map projection) for new data.
Getting help on a tool's environments
A geoprocessing tool can use any number of environment settings. It is up to the developer of the tool to decide which environment settings will be used by the tool. For system tools developed by Esri, the tool help will specify which environment settings apply to the tool. To view this information, do the following:
- Click the Show Help >> button to display the tool's help panel.
- In the tool's help panel, click the Tool Help button. This opens the tool's reference page.
The last section of the tool reference page describes which environment settings the tool will use. Each environment setting is a link to the reference help page for the environment.
Saving environment settings
Application level settings are saved with your document. You can also save your application level settings to a file for later recall or save them as default settings that will be used for all new documents. You do this through the ArcToolbox window.
Environments in tool parameters
Some tools have parameters that take their default value from the environment. For example, the Clip tool has an optional XY Tolerance parameter whose default value is retrieved from the XY Tolerance environment setting.
Environment levels and hierarchy
There are four levels of environment settings: application, tool, model, and model process. All levels contain the same environment variables and have the same effect on output results. They differ only in how you access and set them.
The four environment levels form a hierarchy where the application level is highest. In this hierarchy, environment settings are passed down to the next level, as illustrated below. At each level, you can override the passed-down environment settings with another setting.
The one exception to this hierarchy is with models. If you run the model from the ModelBuilder window, the application environment is passed down. If you run the model using its tool dialog box, the tool environment is passed down.
There are four levels of environment settings:
- Application-level settings are the default and will be applied to any tool when it is executed.
- Tool-level settings are applied to a single run of a tool and override the application-level settings.
- Model-level settings are specified and saved with a model and override tool- and application-level settings.
- Model process-level settings are specified at the model process level, are saved with the model, and override model-level settings.