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Calculating Geometry of Data Collected in UTM

Question asked by Carlynne on May 6, 2015
Latest reply on May 6, 2015 by MKennedy-esristaff

Hi,

 

If I have point data that were collected in UTM based on a datum other than WGS1984, can I use the calculate geometry function to get the point value in lat/long or do I first need to project the data and do a datum transformation before I calculate geometry?

 

I experimented with this by: 1.  importing data collected in UTM based on WGS84; 2. creating two fields for the lat/long values; 3. setting the data frame to WGS84; 4. calculated geometry based on data frame with decimal degrees output versus first projecting the imported data to WGS84 before I do steps 1-4, and I get the exact same coordinate value.

 

I am wondering if this would be the case if the data were collected with UTM based on a local datum. Is it best practice to first project and transform the data before calculating geometry?

 

Any thoughts?

 

Thanks,

Carlynne

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