I'm updating somebody else's old Python scripts, and trying to make sure I understand their logic and desired outputs while streamlining the code. In this particular script, it specifies an output projection in the processing environment settings.

import arcpy

Output_CS = "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',...(etc, etc, etc)"
arcpy.env.outputCoordinateSystem = Output_CS

I think this means that all the subsequent geoprocessing operations (e.g., arcpy.Buffer_analysis) output in WGS84 without needing an additional arcpy.Project_management step.

If that is the case, is there any accuracy risk to running a buffer analysis directly to a geographic coordinate system? In other words, does it do the projecting after the buffer's been appropriately sized?

(The original input data is in a projected coordinate system, one of the NAD83 state plane systems.)

1 Answer 1


if a feature class has a geographic coordinate system AND the buffer is performed with a linear unit (e.g arcpy.Buffer_analysis(input, output, "100 Feet"), ArcGIS will automatically use geodesic distance, which is great. Just make sure that you specify the unit

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