[Therion] Loop problem in extended elevation

Christophe Salti christophe.salti at laposte.net
Fri Aug 13 18:51:59 CEST 2021


Hi Bruce, Xavier,

thanks a lot for your feedbacks. I'll have a deep reading of these pages 
to solve this problem. And furthermore, it will help me understanding 
how Therion is working.

Bruce, I'll also do as you mentioned -having one survey per file- to 
simpify the solving of all these extended centreline problems. It's the 
first time for me dealing with such a complicated cave.

Xavier, I'll come back to you in a private email to find a suitable time 
for you to have a chat on the phone (it was a bit complicated today to 
open my PC).

Cheers and thanks again.

Chris



Le 13/08/2021 11:33, Bruce Mutton a écrit :
>
> Christophe
>
> I agree with Xavier (I think), the breaking extend 
> <https://therion.speleo.sk/wiki/breakingextend> page describes best 
> what is going on.
>
> Follow that up with a look at this page, 
> https://therion.speleo.sk/wiki/extend
>
> Placing ‘log extend’ in your thconfig will help you understand the 
> station sequence Therion is using to develop the extend centreline.
>
> I notice you have many surveys in a single th file.  This means that 
> you have to solve almost all of your extended centreline problems 
> before you will get a meaningful output.  While your surveys are quite 
> short and I can see the temptation to combine them as you have, the 
> interconnectedness makes them quite complicated.
>
> My preferred way of working is to restrict each survey trip/session to 
> a single survey definition, and I would have only one survey 
> definition per file (although the latter I would consider optional).
>
> If you do that, you only need to solve the extended centreline network 
> one survey at a time, adding one more, solving that, adding another, 
> and solving that, etc.
>
> It also means that your xvi file and scrap(s) only need represent a 
> single survey – this is usually much less confusing when you are 
> drawing, both in plan and in elevation.
>
> If, as you do in this project, I have a backlog of undrawn surveys, I 
> tend to resolve the whole extended centreline network before starting 
> to draw the elevation.  Theoretically not necessary, but I have found 
> that the presence of drawings can affect the network development. 
> ‘Drawing last’ like this does not remove the problem, but it does seem 
> to make it both easier to notice, and easier to resolve when it does 
> happen (because you are only fixing one issue in an otherwise resolved 
> network).
>
> Good luck
>
> Bruce
>
> *From:*Therion <therion-bounces at speleo.sk> *On Behalf Of *Xavier Pennec
> *Sent:* Friday, 13 August 2021 20:36
> *To:* Christophe Salti via Therion <therion at speleo.sk>
> *Subject:* Re: [Therion] Loop problem in extended elevation
>
> Salut Chris,
>
> Je pense que c'est le choix de la station ou la boucle est coupee qui 
> est different.
> Voir par exemple : https://therion.speleo.sk/wiki/breakingextend
>
> A priori, il faudrait rajouter
>
> extend ignore #station
>
> pour que la coupe developpée soit coupée a l'endroit ou tu préfères 
> dans chaque boucle.
>
> On peut en parler au telephone si tu veux (mon tel 06 78 35 16 90)
>
> Xavier
>
> Le 12/08/2021 à 18:42, Christophe Salti via Therion a écrit :
>
>     Hi all,
>
>     Hope that someone will be able to help me during this summer
>     vacation, knowing that it's the perfect timing for exploring and
>     surveying caves (but also to do the synthesis of past surveys)...
>
>     So, I'm working on an extended elevation map of a small but
>     complex cave in the South of France (+/- 1500m length & +20/-40m
>     high). Survey was done with a DistoX2 and Auriga (13 surveys were
>     done if I remember but I haven't attached all of these). Most of
>     the cave is made of boulders (énorme éboulis), probably from
>     tectonic origin; so there are plenty of loops (it's a nightmare)
>     and at least 5 or 6 levels. I haven't been working yet on the plan
>     map but I guess it's not going to be a piece of cake (from a loop
>     point of view). Sketches were done by hand to help me during the
>     synthesis. I created an XVI file and I use it as background image.
>
>     I'm working on PC an my therion version is :
>
>
>     So my problem is the following (screenshots below): station 3.2 is
>     unique but there are at least 2 side passages going to different
>     locations of the caves (see screenshots 1a & 1b). During the
>     survey, Auriga was displaying a unique 3.2 station and  different
>     paths (one going to 5.1, then 5.2 and the other one going to 3.11
>     then 3.16 and so on; see screenshot 3 below). But when exported
>     from Auriga into a Therion format and then openned in Therion, I
>     get two 3.2 shifted stations (scale is 1m x 1m), one for each
>     path, as seen in the screenshot 2a.
>
>     Screen shot #1a (sketch: cross section & plan views)
>
>
>     _Screenshot 1b (sketch: cross section view)_:
>
>
>
>     The 2 stations were surveyed at different times (but from the same
>     station/point as stated earlier).
>
>     There are other stations with the same 'shift' problem (I'm only
>     at the begining of the synthesis process). For instance, station
>     5.2 -which comes just after 3.2- is also shifted as seen on the
>     screen shot #2b.
>
>     Is there something wrong I did ? Something I should do instead?
>
>     I've tried to "equate" stations 3.2 and 5.2 (I renamed them before
>     inserting the equate in the survey: first 3.2 in survey #1 is kept
>     as 3.2 but second 3.2 in survey #2 was renamed 3.2bis; same for
>     5.2). Station was shifted/merged of course but I was not able to
>     shift my second 3.2 branch to the 1st one..
>
>     I have checked the very usefull "Therion by example", by Marco
>     Corvi, in the /4.4.2 Loops in extended elevation/ paragraph but I
>     was not able to make it...
>
>     Am I clear enough in my explanations?
>
>     _Screenshot 2a below:_
>
>
>
>     _Screenshot 2b below:_
>
>
>     Why does Auriga is correctly displaying this sort of survey (see
>     screenshot #3 below) and not Therion, by default I mean ? I'm not
>     criticising, of course, it's just a remark from a beginner.
>     -from station 3.2, there are 3 different paths going to 3.11, 5.1
>     and 3.3
>     -from station 5.2, there are at least 2 different paths going to
>     5.47 & 5.3 (there are probably other ways I haven't check)
>
>     _Screenshot #3 below:_
>
>
>
>
>
>     _Screenshot #4 below_: full extended elevation screen as seen in
>     Auriga
>
>
>
>
>
>     Would someone be kind enough to explain me how to deal with it,
>     please? then i should be able to solve most of the others shift
>     problems I'll face during this synthesis...
>
>     Cheers
>
>     Christophe Salti
>     Groupe Speleo de Vence
>
>     ps: I've attached the therion files in case someone could help me...
>
>
>     _______________________________________________
>
>     Therion mailing list
>
>     Therion at speleo.sk <mailto:Therion at speleo.sk>
>
>     https://mailman.speleo.sk/listinfo/therion
>
>
>
> -- 
> > -------------------------
> > Xavier Pennec
> > Senior Research Scientist / Directeur de recherche
> > Epione project-team, INRIA Sophia-Antipolis
> > 2004 Route des Lucioles, BP93
> > F-06902 Sophia-Antipolis Cedex, France
> > +33 4 92 38 76 64
> > +33 6 78 35 16 90
> >https://team.inria.fr/epione/en/
> > -------------------------------
>
>
> _______________________________________________
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> Therion at speleo.sk
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