topic Re: Is it wrong to temporarily switch layer coordinate systems? in Data Management Questions

Is it wrong to temporarily switch layer coordinate systems?

LukeSnyder — Tue, 09 Aug 2016 14:33:46 GMT

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

Re: Is it wrong to temporarily switch layer coordinate systems?

DanPatterson_Retired — Tue, 09 Aug 2016 22:43:48 GMT

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

Re: Is it wrong to temporarily switch layer coordinate systems?

JoeBorgione — Wed, 10 Aug 2016 01:01:05 GMT

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...

Re: Is it wrong to temporarily switch layer coordinate systems?

RobertBorchert — Wed, 10 Aug 2016 20:31:38 GMT

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