Coordinate Origin

[cturlington]

Hello,

I am using Civil 3D 2018.

When I select a state plane reference coordinate system for my cad file, I expect the northing-easting values to read from the origin of the projection and datum, as the two should coincide.  However, if I place the northing-easting grid in a file without a coordinate reference system set, the northing-easting values still read the same.  It seems that by changing coordinate systems from "none" to a "state plane projection", that the origin of the file would move to coincide with the state plane projection, but in my example, the origin remains unchanged.  My question which is somewhat academic, is this: 

how can N-E values read in a file with no coordinate set, the same values as they would in a different file with state plane coordinate system set? 

[tcorey · Accepted solution]

Applying a coordinate system to a drawing will not automatically geolocate objects. You need to use a command that will recognize the difference between source data and target drawing and will do the adjustment for you.

For example, let's say you have a PointFile.txt and the coordinates are UTM-84 Zone 10 North, Meters. You have a drawing in CA83-IF, (Calif Zone 1, NAD83, US Survey Foot.) If you use a simple point import, the importer doesn't know that the incoming data are in UTM or any other system. You must create a Point File Format that tells the importer what coordinate system is being imported, then it can do the conversion.

Or, you have a drawing in UTM-10 and you want to import the linework into your drawing in CA83-IF. Open each and be sure the correct coord system is assigned. Use AutoCAD Map features to Attach and Query from the UTM drawing into the CA State Plane drawing. The query feature knows to do the conversion, if each drawing has an assigned coordinate system.

For more complete advice, post your data.