August 2018 - Therion

Re: [Therion] Eurospeleo 2018
by Bruce Mutton 23 Aug '18

23 Aug '18

Might there be an electronic conferencing option for the cave survey workshop? (a bit late notice I know) Bruce Sent from my Samsung device -------- Original message -------- From: Evaristo Quiroga via Therion <therion(a)speleo.sk> Date: 23/08/18 03:13 (GMT+12:00) To: Stacho Mudrak via Therion <therion(a)speleo.sk> Cc: Evaristo Quiroga <eqr(a)ecgracia.com> Subject: Re: [Therion] Eurospeleo 2018 Hi, I (Evaristo Quiroga) arrive tomorrow 23/8/2018 in the afternoon, and I will be there until 8/27/2018. See you at the welcome ceremony. Regards, Evaristo. El 21/08/2018 a las 15:38, Stacho Mudrak via Therion escribió: Hi everybody, eurospeleo meeting in Austria starts tomorrow. Me and Martin (Budaj), we are leaving there tomorrow and we will be there until Surveying workshop on Sunday afternoon. If you are interested, we could meet at welcome ceremony. S. _______________________________________________ Therion mailing list Therion(a)speleo.sk https://mailman.speleo.sk/listinfo/therion

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Fix station point using only 2D
by Graham Mullan 22 Aug '18

22 Aug '18

I think there are two issues here. I have skewed surveys built on 2D data using 3D fixed points and that seems, to me, to be what is happening here. Firstly, if your radiolocation point has no depth information then you cannot use it for a 3D skew which I think (I may be wrong) as it is insufficiently accurate. Secondly, if your survey is both only in 2D and has an apparent error of as much as 150 m from the radiolocation point then there is something wildly wrong with the data. Your best bet - and yes I have been forced to do exactly this - is to resurvey the cave to 3D standards, whether this be compass/clino or Distox and start again. Sorry, but your dataset is simply not good enough. Graham -----Original Message----- From: Therion <therion-bounces(a)speleo.sk> On Behalf Of therion-request(a)speleo.sk Sent: 22 August 2018 12:00 To: therion(a)speleo.sk Subject: Therion Digest, Vol 152, Issue 9 Send Therion mailing list submissions to therion(a)speleo.sk To subscribe or unsubscribe via the World Wide Web, visit https://mailman.speleo.sk/listinfo/therion or, via email, send a message with subject or body 'help' to therion-request(a)speleo.sk You can reach the person managing the list at therion-owner(a)speleo.sk When replying, please edit your Subject line so it is more specific than "Re: Contents of Therion digest..." Today's Topics: 1. Re: Fix station point using only 2D (kevin dixon) 2. Re: Fix station point using only 2D (Martin Sluka) 3. Re: Fix station point using only 2D (Xavier Pennec) 4. Eurospeleo 2018 (Stacho Mudrak) ---------------------------------------------------------------------- Message: 1 Date: Tue, 21 Aug 2018 11:06:05 +0100 From: kevin dixon <geospatial3d(a)gmail.com> To: List for Therion users <therion(a)speleo.sk> Subject: Re: [Therion] Fix station point using only 2D Message-ID: <CAAUsM%2BNn7MgMkKaSMuJJhfVwTvot2RiNcnHdS5%2BRuP97D_2iAA(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" Adam, Radio-location can give you depth but accuracy is not too good. How have your surface positions at the entrance(s) and the radio location been determined ? Professional GNSS (~3cm), DGPS(~1m) or hand held (~3m) ? I have radio-location fixes at the far end of a system to control any accumulated azimuth bias. For these I have assigned an elevation to the radio-location equivalent to the cave survey at the radio location point and used an appropriate SD value for the radio location data. You may have to iterate a few times and experiment with SD values to see how it changes your survey with and without the radio location fix(s). Also better if you have radio location fixes at different points because geology effects the position. Use several in the survey - you should see how they fit (or not) - reject the wildly out ones, adjusting to the rest will help reduce any bias. 150m is a lot of difference so I would be looking at the positional method used, datum and grid, survey instrument calibrations, declination values and then get additional radio locations to confirm. If you are dealing with older survey data then you may want to consider a compass bias - does a survey rotation significantly reduce the difference ? Kevin Dixon On Tue, Aug 21, 2018 at 10:41 AM, Adam Pyka via Therion <therion(a)speleo.sk> wrote: > Hi all, > > How to 'fix' the survey station point (to morph the cave plan) having > only 2D coordinates? > > Using the radiolocation we get (with quite good accuracy) the station > point position which is about 150m beyond the estimated location we > get from surveying. So now I wanted to use this position to make a > correction to the main polygon. But the 'fix' command need a 3D coords > so how should I do that (no, there is no point to measure the depth by > radiolocation by some reasons). > > Thanks in an advice, > Adam > _______________________________________________ > Therion mailing list > Therion(a)speleo.sk > https://mailman.speleo.sk/listinfo/therion >

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Re: [Therion] Fix station point using only 2D
by markus.boldt＠gmx.net 22 Aug '18

22 Aug '18

Hi Adam, "normally" you have coordinates of your radio location point at the surface from GPS. You know, I do so. What a kind of coordinates you have? Give them simply a thought depth for example. Best regards to Poland and greetings to Agnieska :-). Markus -----Ursprüngliche Nachricht----- Von: "Adam Pyka via Therion" <therion(a)speleo.sk> Gesendet: Dienstag, 21. August 2018 11:41 An: therion(a)speleo.sk Cc: adampyka(a)gmail.com Betreff: [Therion] Fix station point using only 2D Hi all, How to 'fix' the survey station point (to morph the cave plan) having only 2D coordinates? Using the radiolocation we get (with quite good accuracy) the station point position which is about 150m beyond the estimated location we get from surveying. So now I wanted to use this position to make a correction to the main polygon. But the 'fix' command need a 3D coords so how should I do that (no, there is no point to measure the depth by radiolocation by some reasons). Thanks in an advice, Adam _______________________________________________ Therion mailing list Therion(a)speleo.sk https://mailman.speleo.sk/listinfo/therion

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Eurospeleo 2018
by Stacho Mudrak 22 Aug '18

22 Aug '18

Hi everybody, eurospeleo meeting in Austria starts tomorrow. Me and Martin (Budaj), we are leaving there tomorrow and we will be there until Surveying workshop on Sunday afternoon. If you are interested, we could meet at welcome ceremony. S.

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Fix station point using only 2D
by Adam Pyka 21 Aug '18

21 Aug '18

Hi all, How to 'fix' the survey station point (to morph the cave plan) having only 2D coordinates? Using the radiolocation we get (with quite good accuracy) the station point position which is about 150m beyond the estimated location we get from surveying. So now I wanted to use this position to make a correction to the main polygon. But the 'fix' command need a 3D coords so how should I do that (no, there is no point to measure the depth by radiolocation by some reasons). Thanks in an advice, Adam

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Re: [Therion] SDs for distoX surveys
by Graham Mullan 15 Aug '18

15 Aug '18

I am not sufficiently versed in the maths to suggest what figures might be used, but I do want to know why you think that the 3-times feature might affect the expected error for the angles but not for the length? Graham -----Original Message----- From: Survex <survex-bounces(a)survex.com> On Behalf Of Wookey Sent: 04 August 2018 01:37 To: Survex User Group <survex(a)survex.com>; Therion List <therion(a)speleo.sk> Subject: SDs for distoX surveys Has anyone thought about what the correct SDs for distoX/distoX2 (as opposed to compass and tape) surveys are? I reckon distoX surveys have significantly lower expected error, due to the 'measure 3 times' leg feature (if used) and just higher accuracy due to instrument itself, ease of taking readings (no need to get head near station), and no difficulties with steep legs > 15 degrees. Seems to me this means that we should be using different SDs for these surveys (at least for bearing and inclination readings - length is not obviously more reliable), but I'm not sure how to quantify those improvements. Anyone got any ideas what numbers to use? Wookey -- Principal hats: Linaro, Debian, Wookware, ARM http://wookware.org/

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Survey Data Format - backclino
by Torsten Schnitter 14 Aug '18

14 Aug '18

Hi List I'm using this data lines for survey: data normal from to left right up down tape compass backcompass clino backclino In general all data is available, but in some point I have some missing data like LRUD, Compass/Backcompass or Clino/Backclino. When I have missing LRUD data or missing backcompass I put in a minus "-" and this is OK. But when I use "-" for backclino I get an compilation error: reading source files ... C:\Program Files (x86)\Therion\therion.exe: error -- ....filename.... -- invalid backwards gradient reading -- - writing xtherion file ... done Is this a bug? Because for LRUD and Backcompass minus sign is working fine. What sign can I use for missing backclino readings? regards, Torsten

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SDs for distoX surveys
by Wookey 04 Aug '18

04 Aug '18

Has anyone thought about what the correct SDs for distoX/distoX2 (as opposed to compass and tape) surveys are? I reckon distoX surveys have significantly lower expected error, due to the 'measure 3 times' leg feature (if used) and just higher accuracy due to instrument itself, ease of taking readings (no need to get head near station), and no difficulties with steep legs > 15 degrees. Seems to me this means that we should be using different SDs for these surveys (at least for bearing and inclination readings - length is not obviously more reliable), but I'm not sure how to quantify those improvements. Anyone got any ideas what numbers to use? Wookey -- Principal hats: Linaro, Debian, Wookware, ARM http://wookware.org/

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therion website not secure
by Bruce Mutton 03 Aug '18

03 Aug '18

Is there a problem with the Therion website? My browser is complaining that the https is no longer working. Bruce

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