I know how to convert from grid to ground in TBC. How can I convert back to grid coordinates from ground in TBC?

I know how to convert from grid to ground in TBC. How can I convert back to grid coordinates from ground in TBC?

Terry:

Thanks for your reply!

Would you mind clarifying the term “Origin”?

I believe you are speaking of the coordinates for the base point of the State Plane Zone, but am not certain.

Thanks so much!

Gary

The origin I am speaking of is the origin of the scale. This value is the coordinate you entered, either NE or LL in Local Site Settings. This is the location of where the points will be scaled from so it's value will not change. Some States DOT's hold 0N, 0E as the fixed coordinate so that all of the state plane values will increase to the north and to the east (assuming all values are positive). If you were to enter a value in the center of the project, the scaled points will be scaled radiating from that center coordinate. Hope this helps.

Terry:

First, thanks for your reply. As I said, initially it is my intention to convert back to grid in TBC.

I understand your statement: “This value (the Origin) is the coordinate you entered, either NE or LL in Local Site Settings.” Unfortunately, I did not record the coordinate for the Origin in the TBC procedure. So, I am unable to proceed.

Do you know of a way to extract these coordinate from TBC?

Thanks,

Gary

To do this you must know a few things about the ground coordinates..

This then could be done in Excel. You would find the difference from the ground coordinate to the origin point.

Multiple that diff by the inverse of the grid to ground SF and add that back to the Origin coordinate.