Is it wrong to temporarily switch layer coordinate systems?

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08-09-2016 07:33 AM
LukeSnyder
New Contributor III

I want to temporarily change my layer coordinate system from a state plane to WGS 1984, use the Geometry Calculator to populate  Lat / Long fields, then switch it back to my state plane.

Would this cause any issues?

I've read a number of longer work arounds, but curious if this is an acceptable method.

Thanks in advance

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DanPatterson_Retired
MVP Emeritus

it is fine to temporarily switch, do the calculations, then switch back.  Alternately, you can just use the tool in arctoolbox and specify the coordinate system there.

Add Geometry Attributes—Help | ArcGIS for Desktop

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3 Replies
DanPatterson_Retired
MVP Emeritus

it is fine to temporarily switch, do the calculations, then switch back.  Alternately, you can just use the tool in arctoolbox and specify the coordinate system there.

Add Geometry Attributes—Help | ArcGIS for Desktop

JoeBorgione
MVP Emeritus

It's been a while since I've noticed a black SUV with FPPEA ( Federal Projection Protection & Enforcement Agency) emblazoned on the doors.  Pretty sure they are laying low until after November.  Now's a really good time to follow Dans advice and go for it.  But if anyone asks, you heard it from him.  Not me... 

That should just about do it....
RobertBorchert
Frequent Contributor III

Specify the coordinate system you want to use in a blank session.

Add the features you want to calculate.  Create your Fields and use the calculate Geometry tool.

Specify to use the coordinate system of the data frame.

If you don't specify the projection before you add the data it will default the data frame to the projection of the data.

You can also specify the data frame projection after you add the data.

However, I don't think you really need to do that.

Using the calculate Geometry tool if you select Decimal Degrees as you units. It will calculate it in Decimal Degrees.  I do this quite often in my State Plane projections and then use the resulting X,Y to generate new features using WGS84