Coordinate conversion with Add Geometry Attributes vs Calculate Geometry Attributes

03-02-2022 12:58 PM
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Occasional Contributor III

I recently had to convert coordinates into several different coordinate systems and I just now realised when I double-checked the exported table (re-importing it into GIS, data as x,y for different coordinates) that I sometimes had a slight transformation error, where all my points had shifted slightly.

I did find out that it was due to using "Add geometry attributes" for UTM coordinates while the layer and map frame was in WGS84. I also found out that I can avoid this by:

a. Changing the map frame CRS

b. Adding a transformation to the CRS

c. Projecting the feature class to the UTM

d. Using Calculate Geometry Attributes instead.

All of the above gave me slightly different coordinates (in the decimal places). Now my questions are:

1. Why does Calculate Geometry Attributes work, when Add Geometry Attributes doesn't? What do the two tools do differently?

2. Which would be the most accurate way to calculate the coordinates? I would have thought to use "Project" and the Calculate Geometry Attributes, however, in my field test, those two points were further apart than the other options.

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MVP Esteemed Contributor

Calculate Geometry Attributes (Data Management)—ArcGIS Pro | Documentation

Add Geometry Attributes (Data Management)—ArcGIS Pro | Documentation

Calculate Geometry supports geographic transformations as an environment variable.  It  would be the one that I use should I need to perform a projection and transformation.  You will have to compare for any subtle differences in the other geometry returned parameters, or examine the scripts for other differences in parameters and arc* stuff used

C:\...Your_install_folder ...\Resources\ArcToolBox\Scripts

... sort of retired...
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