> If there is a real need for a switch between converting and not > converting the heights, let us know.
At least here in the UK, a lot of rough and ready surveys seem to use Garmin handheld GPS units like the 66sr. These use barometric altitude, which you calibrate to a local benchmark. That means you get local mapping heights that do not need to be converted, while the GPS coordinates would need to be converted. Anyone relying on this approach (which already is rather poor from an accuracy perspective) would indeed need you to perform conversion on x and y but not z, while anyone using a proper GPS unit which outputs ellipsoid heights would need you to convert x, y, and z. I therefore see a need for it to be controllable. Personally, I use real GPS ellipsoid heights, which I manually convert using continental drift calculations and the higher quality OSTN15+OSGM15 transformation (since these then remain correct in spite of continental drift). I do not rely on proj for that, and have built my own tool instead, since proj does not have access to the data required for it. Tarquin _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
