> Theodolites are not really set up for doing traverses, for a loop of a few > hundred metres we have an mis-closure of about 1m. I would be disappointed if > I was using a disto X. It seems to be par for the course. The show cave > owners paid for a traverse when they where tunnelling. They claimed > millimetre accuracy however were metres out. Lead to a bit of an arguement > between the caver surveyors and the paid surveyors about Which direction to > dig the tunnel. It was resolved when the tunnel broke through. Luckily the > tunnelers listen to the cavers. 😁
Well, that saves me buying one (as if I could afford one). I was expecting them to be super-accurate, if calibrated properly. I'm assuming this is not a calibration issue though. Theodolite grades were always given as being so much higher than regular surveys, so this is quite eye-opening. Presumably the existing "theodolite" mode you were referring to in Survex/Therion is designed for use with separate positioning and levelling, since levelling gives extremely high accuracy vertical position, so all you need then is the horizontal. (This is similar to how OS land surveys were traditionally done, with the horizontal and vertical surveys being almost entirely unrelated, and only tied in a few places for convenience.) I will add a note that yes, out-of-range crazy numbers is actually normal with theodolite-style devices. Not just for inclination. Certainly there are some other surveys done with thodolites (both professional and home-made) where the compass bearing is over 360, with full wrap-around. One other things I just learned from this thread; degrees:minutes:seconds is a supported format. Cute. Useful for optical theodolites which are actually accurate enough to measure in such tiny increments. Never seen it in a cave survey before. _______________________________________________ Therion mailing list [email protected] https://mailman.speleo.sk/listinfo/therion
