Changing units of buffer

Question

Desktop 10.3.1 GCS: WGS 1984

Created a Buffer of points based on a pre-specified radius from the points attribute table.

It appears all of the buffers were created with a decimal degree unit of measure.... How do I change the units of the buffer layer to miles?

Answer 1

Riffing off what @scw wrote, the buffer process will take the appended unit ("# Miles") as an input as per the ArcPy script:

arcpy.Buffer_analysis("input_points", "C:/workspace/points_buffered_10mi.shp", "10 Miles")

You could create a new string field with field calculator where you take the distance number and add " Miles" to it. The field calculation would look like (in python):

str(!field!) + " Miles"

You should then have a string field of "## Miles". Point to that new field as the distance field when you run the buffer and it should work.

EDIT: I just confirmed that this works. I made a group of points and assigned them random numbers, did the concatenation. Ran through the buffer just fine. My table looks like this:

EDIT 2, for posterity: The details on this can be found on the ArcGIS resource site here: Buffer (Analysis)

Answer 2

It isn't clear exactly how you created your buffers from your question, but my guess is that you're trying to use attributes of the PointGeometry representation and using the buffer function included with that representation. By default, that buffer function is limited to buffering in the same units as the input data, which in your case with unprojected geographic data, doesn't make sense -- a unit of degree varies with both latitude and longitude.

The easiest thing to do is to use the Buffer tool, which takes a linear unit for the parameter buffer_distance_or_field, and will automatically create geodesic buffers if passed in miles:

import arcpy
arcpy.Buffer_analysis("input_points", "C:/workspace/points_buffered_10mi.shp", "10 Miles")

Here's the set of linear units buffer will understand: 'Centimeters', 'Decimal degrees', 'Decimeters', 'Feet', 'Inches', 'Kilometers', 'Meters', 'Miles', 'Millimeters', 'Nautical Miles', 'Yards'