<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr"></div><div dir="ltr">You could also indicate the misalignment with instrument correction commands, but i dont know the exact command at the moment. I think that would not with different orientations of the same device...</div><div dir="ltr"><br>Am 05.09.2019 um 13:10 schrieb Max D <<a href="mailto:md@foxel.org">md@foxel.org</a>>:<br><br></div><blockquote type="cite"><div dir="ltr"><meta http-equiv="content-type" content="text/html; charset=utf-8"><div dir="ltr"><span></span></div><div dir="ltr"><br class=""><br class=""><blockquote type="cite" class="">On 5. Sep 2019, at 08:28, Olly Betts <<a href="mailto:olly@survex.com" class="">olly@survex.com</a>> wrote:<br class=""><br class="">On Fri, Aug 16, 2019 at 05:11:22AM +0200, MD wrote:<br class=""><blockquote type="cite" class="">We also then to measure the same small loop at the beginning of each trip: <br class="">A-B in four device orientations<br class="">B-A in four device orientations<br class="">A-C in four device orientations<br class="">C-A in four device orientations<br class="">C-B once<br class=""><br class="">So I could calculate an SD based on that. <br class=""></blockquote><br class="">You probably don't want to work out a set of SDs per-trip - </blockquote><div class=""><br class=""></div><div class="">Currently we set the SD per calibration - which works out to about every second trip. We Take the "Error stddev" from Topodroid Calibration Results - e.g.0.1058 in the attached Screenshot.</div><div class=""><br class=""></div><div class="">Thinking of it, this might be the wrong approach because it only considers the instrument.</div><div class=""><br class=""></div><blockquote type="cite" class="">*sd tape 0.002 metres ; 2 millimetres<br class="">*sd compass clino 0.5 degrees<br class="">*sd position 0.05 metres ; 5 centimetres<br class=""></blockquote><div class=""><br class=""></div><div class="">Interesting. I will read up on the difference between tape and position</div><br class=""><blockquote type="cite" class=""><blockquote type="cite" class="">For sone Devices errors seem to be bound very much to orientation. In<br class="">the data saved by TopoDroid you can see the device orientation and so<br class="">we could set a sd based on the direction in which the shot was taken.<br class="">I have nit investigated this further so far. Also because we have this<br class="">data only for about 20% of the cave.<br class=""></blockquote><br class="">This is already taken into account - you tell Survex the SD for the<br class="">"tape" (read laser range-finder), "compass" and "clino" (read magnetic<br class="">field measuring devices) and position (how close to the station you<br class="">actually measure from) and it uses the direction of the leg to produce<br class="">a 3D set of expected errors, which are then summed along each traverse.<br class=""></blockquote><div class=""><br class=""></div><div class="">But I would need a extra set SD data per device orientation. </div><div class="">So I know that if the display is to the right the Disto tends to reassure an Azimuth 2 degrees to high and if the display is to the left.</div><div class="">And when the display is to the left it tends to give an Azimuth 1 degree to low.</div><div class=""><br class=""></div><div class="">But perhaps I just should try to do more and better calibrations instead of fixing stuff afterwards.</div><div class=""><br class=""></div><br class=""><blockquote type="cite" class=""><blockquote type="cite" class="">TopoDroid also is able to flag an “magnetic anomaly” - i’m not totally<br class="">sure how but this als could be used in setting a per shot SD. i have<br class="">not looked much into this.<br class=""></blockquote><br class="">I think you want to treat that as an in-cave indication that you should<br class="">check for sources of magnetic interference and redo affected readings.<br class=""></blockquote><div class=""><br class=""></div>Good Advice!<div class=""><br class=""></div><div class="">Thanks!</div><div class=""><br class=""><div class="">--max<br class=""></div><div class=""><br class="webkit-block-placeholder"></div><Screenshot_20190720-135115_TopoDroid.jpeg></div></div></div></blockquote><blockquote type="cite"><div dir="ltr"><span>_______________________________________________</span><br><span>Therion mailing list</span><br><span><a href="mailto:Therion@speleo.sk">Therion@speleo.sk</a></span><br><span><a href="https://mailman.speleo.sk/listinfo/therion">https://mailman.speleo.sk/listinfo/therion</a></span><br></div></blockquote></body></html>