We have a Trimble GPS unit we use to collect system assets.
We collect the data in WGS84 and differentially correct it, and then reproject it into our State Plane Coordinate System.
The resulting points always shift the same distance in the same direction after the reprojection.
Any idea what could cause this?
It may be a lack of datum transformation in your projection operation.
Your symptom sounds familiar. It is a common problem here in Wisconsin - GPS uses the WGS84 datum, but our state system uses NAD83HARN.
The symptom of doing a projection without datum transformation is that coordinates are systematically offset a few meters in X and ~meter in Y.
