There are several options here. Some are one-time and basically permanent, others are removeable and allow for future data to be incorporated without further adjustment.
If you just want a simple, one-and-done solution that will produce points with shifted elevations (but doesn't provide good provisioning for future additional work on this datum):
- Use Excel to shift the elevations before importing into other programs, or re-import the values back into TBC. I believe you can clear the northing/easting columns and import the CSV as "control quality" and you should get just elevations, which will allow for the horizontal position of your points to continue to be adjusted. If you bring data back into TBC like this, you'll end up with flags on every point.
- Use the Transformation tool
The reason to
not use one of these options is that it pretty much kills the workflow if you want to bring in more data later. The transformation tool is a one-time thing and there's no simple way to "clear" it later on (i.e. it does
not work like a site calibration or network adjustment that have a "clear" button).
The other option, and the one I prefer, is to use a site calibration. This does require that your survey field work be conducted in a particular manner, however. I don't know the specifics of your project, but basically you need a way to propagate (at least one) GPS-derived elevations throughout all of your total station setups. This can be achieved by traversing as long as your first instrument setup point (and preferably the backsight point) were tied in with GPS. If all of your control is shot with GPS, you're good. Another option is to use a level, again depending on how your survey network is setup this is probably the best and most foolproof method - you would simply need to update your BM elevation and then apply a calibration to your project to correct any GPS-derived elevations.