We are changing a coordinate system in an existing TBC project. The office entered grid coordinates are changing by -408mm in the easting and +332mm in the northing when the coordinate systems are changed.

TBC Project with coordinate system "A". This project contains a site calibration with horizontal and vertical parameters.

This is the same TBC Project, but it contains a new coordinate system "B". This project contains no horizontal or vertical calibration parameters.

Is there a reason why the grid coordinates have changed? I would have thought the grid coordinate (set to control status) should be the same in all projects irrespective of any coordinate system selected?

Cheers

Liam

Is point RP510 a point of origin in your site calibration in coordinate system A? If not, then removing the site calibration will change all the coordinates in your project. Either way, removing the site calibration will change the values of points in your project.