[Therion] Good practices for xvi files?

[knollesimage at t-online.de]

Hello Jean,
I work with one xvi file per survey trip, sometimes it's necessary to overlay them (referencing multiple xvi in *.th2 file.

Regards, Michael.

-----Original Message-----
From: Therion <therion-bounces at speleo.sk> On Behalf Of Jean-Florent Raymond
Sent: Donnerstag, 17. September 2026 08:40
To: Therion List <therion at speleo.sk>
Subject: [Therion] Good practices for xvi files?

Hi all,

I have some problems with xvi files so I wonder if I do things the right 
way.
Like many of you I guess, I use to draw incrementally. That is, I have a 
therion project that compiles to a map of a cave we are currently 
exploring and when we discover new stuff, we survey it and I add it to 
the map with the following steps:

1. Add the new data in a new th file to the project folder.
2. Compile to update the xvi file.
3. Open the drawing with xtherion and draw the part of the cave 
corresponding to the new data.
4. Compile to get a pdf.

(in particular in this example there is a unique xvi file and a unique 
th2 file for the whole cave)

The problem is in step 3 when I open the drawing with xtherion. 
Sometimes the updated xvi is shifted compared to the existing drawing, 
possibly because it does not have the same dimensions as previously. 
This is annoying but can be fixed by manually positioning it. However if 
I close a loop then the xvi centerline is distorted (to distribute along 
the loop the unavoidable error) so in xtherion the previously draw map 
does not correspond at all to that centerline.
Problems:

- I have to position the xvi manually (this cannot be avoided I suppose)
- Only the new parts of the cave can be drawn on the xvi, because the 
old ones do not correspond anymore. In particular I cannot easily rework 
previously drawn parts of the cave.

I tried to think of different solutions:

a) Generate a different xvi file for each time I add data, so that I can 
always open in xtherion an xvi file that matches the part of the drawing 
I am interested in.
b) Accept that the xvi file will only match the latest part of the 
drawing and each time I add data, fix it position with respect to the 
station where the new data starts.
c) Use a version control software like git, so that I can easily find in 
the history a version of the xvi file matching the part of the drawing I 
want to work on. (I would like to avoid this option because when 
teaching therion to beginners there is already a lot to tell and I do 
not want to add git on top of that.)

What about you, how do you deal with that?

Best,
Jean-Florent.
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