Coordination Transformation

[Anonymous]

Hello, I am giving a drawing containing all the contour objects in a NAD 83 coordination, I need to transfer them to a project coordination system.  I am given with the origins of both system.  For NAD 83, it is N6360000 E467000, for the project it is N50000 E8000.  I tried to do the transformation using Toolspace->Settings->Drawing Settings->Tranformation, and changed the Local Northing/Easting and Grid Northing/Easting, but does not seem to solve the problem.  Any help is appreciated.

Thanks. Jacky

[AllenJessup]

I could go in to how complicated this can become. To do a proper transformation you need to know a lot more that the difference in origins. Things like how far from the geoid the local net is.

Since this is obviously an arbitrary ground based system. I'm sure that none of the necessary information is available. If this is a small project area you can probably get away with the old Move, Rotate and Scale trick, You need to have 2 points common to both systems to do this. Ideally either control points or hard objects like concrete platform corners. You'll also have to deal with elevation discrepancies.

My suggestion to you is: Send someone who has Survey Grade GPS out and get the control for the ground Survey coordinated. BTW. There are MANY NAD83 based coordinate systems. So you will have to know which one you're aiming for. Bringing the ground data in to a real world coordinate system going to yield much more stable results.

More reading on coordinate systems:

Coordinate Transformations in Civil 3D

WORKING WITH GRID COORDINATES

Allen Jessup