> instead Toporobot just generates a new station for the backsite. PocketTopo automatically detects backsights if they are taken immediately after a foresight. So the software handles the station naming, no user intervention required. While I processed the only survey I ever did this way with Therion, it never made it into the main cave dataset and so I didn't get as far as checking the survey length was correct (or doubled). I'm pretty sure it would be correct though. It was only done to find a reasonably precise gap in an 'almost looped' passage. The gap was too big to dig so we lost interest and I haven't drawn the enhanced accuracy map yet. It is at the bottom of my priority list. The exercise was also helpful to gauge the frequency and size of foresight/backsight mismatch with 'three-shot' disto readings. My conclusion: a few instances that may be of interest occur, but not enough to ever bother actually taking all those backsights. Have never done a backsight since. Our disto driven loop closures are typically 0.5% (I like to think) but a bad one will be 1.0%. Compared to our pre-disto loops over a decade ago which were typically 2% and a good one 1%. Although I prefer to think in Survex's standard deviation approach to loop closure, which tells a different story about which loop is good and which not... Bruce
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