Converting State Plane Easting/Northing to Decimal Degrees?

[JonathanNewell]

I was given 20 points from my supervisor that were taken in Illinois State Plane East. I put those points into an excel spreadsheet and brought them in to Arc and assigned them the coordinate system that they were taken in. My supervisor has asked me to convert them to decimal degrees through ArcMap and suggested adding fields and using the calculate geometry function to generate the decimal degrees for each point. I have tried doing this but every time I get results to the fields it just ends up being the Easting/Northing values and not decimal degrees.

Any suggestions would be very helpful!

Thank you

[JonathanNewell]

I think I have figured it out.

I changed the coordinate system of the data frame from a projected to a geographic and then when I ran the calculate geometry, it seems to have worked.


J. Newell

[RichardFairhurst]

I was given 20 points from my supervisor that were taken in Illinois State Plane East. I put those points into an excel spreadsheet and brought them in to Arc and assigned them the coordinate system that they were taken in. My supervisor has asked me to convert them to decimal degrees through ArcMap and suggested adding fields and using the calculate geometry function to generate the decimal degrees for each point. I have tried doing this but every time I get results to the fields it just ends up being the Easting/Northing values and not decimal degrees.

Any suggestions would be very helpful!

Thank you

You can change the projection of the Map Data Frame to a Geographic Coordinate System that uses Decimal Degrees, like WGS 84, by right clicking on the map and accessing the data frame's properties.  Choose the coordinate system tab and set an appropriate transformation from your Illinois State Plane East projection and accept the changes.  Then in the table view of the points, right click the field you want to calculate the logitude or latitude into and choose the Geometry Calculator.  In the dialog choose the appropriate X or Y coordinate for the long or lat and then select the option to use the Data Frame's projection instead of the feature class coordinates.  Decimal Degrees is the default for the WGS 84 spatial reference.  Press OK and the Decimal Degree coordinate should be calculated into the field.

If you export the point data from the table view to a new table (.dbf or geodatabase table, I prefer geodatabases), you can use the Make XY Event Layer tool to create a point layer that uses the lat and long coordinates and the WGS 84 projection.  If you then export that layer from the TOC of the map it will permanently store a feature class of points that uses the WGS 84 coordinate system if that is the end result you are looking for.

Reset the data frame's projection back to State Plane if you intend to edit or create new points in the original points feature class, since it is not a good idea to edit features when there are different projections on the feature class and the data frame.

[JonathanNewell]

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Thank you! This is what I ended up doing.