Large decimal degree values when calculating geometry for latitude and longitude

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09-24-2020 11:19 AM
BrentDavis
New Contributor II

Often we need to edit a polygon feature and recalculate a longitude and latitude field for the centroid of the feature.  Historically, we have been doing this editing calculation within arcmap, but have been trying it out in ArcGIS pro.

Unfortunately when we try and calculate the centroid x-coordinate and centroid y-coordinate for longitude and latitude in decimal degrees we are getting very large values as compared to the workflow used in arcmap.  It looks like the format is being displayed in meters.

Below are the setting we are using:

Here is the output of (Lat,Lon) for a test feature that was created.

Any ideas on how to reproduce the calculate geometry function from arcmap?

Thanks

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10 Replies
DanPatterson
MVP Esteemed Contributor

what are you using to calculate the values?  It looks like your data are in a projected coordinate system or it has been defined incorrectly as geographic when it is indeed projected


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BrentDavis
New Contributor II

Dan thanks for your reply.

I am not sure where to find this out. These are the spatial reference properties of the feature layer in question.

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DanPatterson
MVP Esteemed Contributor

right-click on the layer, select properties, look for spatial reference.

Again, what did you use/do to calculate the values for the coordinates?


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BrentDavis
New Contributor II

We are right clicking a field in the attribute table for the layer and clicking on 'Calculate Geometry'. I believe this is the same thing as using the 'Calculate Geometry Attributes' geoprocessing tool.

I've screenshot two images: The Calculate Geometry tool and the Spatial Reference information for the layer.

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DanPatterson
MVP Esteemed Contributor

You do have a projected coordinate system, it seems that the long/lat output request isn't being supported

Use

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

to compare


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BrentDavis
New Contributor II

Attached is the settings used for Add Geometry Attribute and what attributes were created for a selected feature.  Looks like I'm getting the same values.

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DanPatterson
MVP Esteemed Contributor

So confirmed that the data are in a projected coordinate system.

Now try to get them calculated in a GCS NAD83 (geographic coordinate system) to get them in decimal degrees,

You might have missed the help section....

If a coordinate system is specified, the length and area calculations will be in the units of that coordinate system unless different units are selected in the Length Unit and Area Unit parameters.


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BrentDavis
New Contributor II

O.k. GCS NAD83 did work for the coordinate system.  Thank you.

Is this because I was using a PCS for my coordinate system but decimal degrees should be using a GCS?  

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DanPatterson
MVP Esteemed Contributor

Yes... GCS (geographic coordinate systems) are in decimal degrees. 

PCS (projected coordinate systems) are usually in meters, but a few countries opt for feet (international or U.S.)

Datums are a whole different issue... basically describing Earth's shape (simply) so if those fundamentals change, then coordinate values will change for a fixed location on Earth... hence, referred to as "datum shift".

There are tons (or tonnes) of great references out there


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