I try to get people to rotate the distox when taking some/all readings depending on there keenness and how easy it is*. The distox records and sends its rotation to pockettopo and I put this into the therion/survex file. So should the rotated leg have a different sd to the none rotated, probably. It would be useful if therion/survex could do this automatically from the readings but I guess that would require there to be a rotation field in *data *rotation is a partial check on calibration and generally picks up local magnetic interference, so at a minimum rotate every 5 or whenever we suspect metal. Andrew On Wed, 15 Aug 2018, 15:23 Footleg, <drfootleg@gmail.com> wrote:
In my own experience, the most common blunder which the 'measure 3 times' method with DistoX2 catches is mis-read distance. The Disto tends to be used in the same orientation for all 3 shots, so the compass and clino tend to be well aligned in all 3 (regardless of how well calibrated the DistoX is, or is there are local magnetic fields throwing the compass). But the laser does sometimes miss the target and overshoot, resulting in one of the 3 shots being out of tolerance for PocketTopo to count them as a valid leg. Of course catching blunders so they never make it into the data (we would reshoot when it happens) is not the same as the SD in the measured data.
The way we catch bad calibration problems or local magnetic interference is to take backshots (3 of them). This has saved serious errors on multiple occasions which would not have been detected taking shots in one direction alone.
Footleg -- Survex https://lists.survex.com/mailman/listinfo/survex