[Therion] Loop problem in extended elevation

Fri Aug 13 11:33:24 CEST 2021

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...

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-- 
> -------------------------
> 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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