Tools that honor the Reference Scale environment will consider the graphical size and extent of symbolized features as they appear at the reference scale.
- The reference scale defines the scale at which symbols appear at their intended size. When a reference scale is set, changes in scale result in symbols changing size relative to surrounding features. If no reference scale is set, symbols remain a constant size and do not change size relative to surrounding features.
- When the Reference Scale environment is undefined, its value is taken from the reference scale of the active data frame used, if a data frame is accessible. If a data frame is not accessible (because you are running tools in a script or outside the application) and the Reference Scale environment is left undefined, you are likely to encounter errors in any tool that must assess the graphical size and extent of symbolized features.
Reference Scale—The denominator of the scale fraction corresponding to the intended display scale of input data.
arcpy.env.referenceScale = double
The denominator of the scale fraction corresponding to the intended display scale of input data
# Set the reference scale to 1:25,000
arcpy.env.referenceScale = "25000"