[Therion] Aligned cross sections for multiple passages

[Bruce Mutton]

Interesting...

When I finished my initial Therion learning phase I thought about aligned cross sections through stacked passages, and decided I had bigger problems to solve (ie it was too hard).  So glad you are exploring this!

 

Not sure I am keen on duplicating data, but can see it might be tolerable as a means to an end.

Wondering why you think that colour by altitude won't work with the method you describe?  I would think it would - although you might need to draw several scraps for a tall piece of passage to colour it nicely.

 

Seems to me there might be a number of approaches to the general problem, depending on one's pragmatic-perfection quotient, and on the information you already have.

I also have not tested these approaches – just brainstorming.

1.	If you have individual sections already drawn, you can position them individually the usual way, and attempt to lay them out manually in more or less the right position by trial and error.  This will give a poor result, but if you are not fussy, it will be easy.
2.	If you have individual sections drawn, and can get them aligned properly in the same image, then just scan that image and use it as a background in your th2 file, trace it, and reference a station in each passage (it will need to be at the top level of your survey to be able to reference different sub-survey branches) or just one station if you are closer to the pragmatic end of the scale.  You can probably then treat this as a single section and scrap of -projection ‘none’.
3.	Or as with approach 2 but treat it as -projection [elevation 355 deg] similar to what Tarquin has suggested.  So long as you have a station in each passage, Therion should now morph the individual passages into the correct locations.  There may well be some undesirable distortions if your sketched relative locations are too far out. 
4.	Or duplicate some data and draw the aligned cross section of stacked passages from scratch as Tarquin suggests in the wiki page.  Probably close to a perfect result.

 

The fundamental relationships between scrap and map definitions in your particular dataset may have an impact on the behaviour of each of these approaches (ie works or not, easy or hard). (Remember this <https://www.mail-archive.com/therion@speleo.sk/msg06555.html>  a couple of years ago?)

I wonder if an approach similar to what I have used for separating control of extended elevations from the main survey centreline <https://therion.speleo.sk/wiki/extend>  can be used?  ie, alias the information you want in the section without duplicating it.

At this stage concepts I can envisage either result in station and splay overload as previously described, or stations without any splays, neither of which is that useful.  Centrelines can have their own -id, so maybe there is something cunning that could be done by putting each of the ORIGINAL section stations and splays in their own centrelines within their parent trip surveys.  If these centrelines were in their own th files, they could be input into both  their parent survey file and a section th file. Hmm, sounds messy in practise with all that metadata duplication.  Probably Tarquin’s way better!(?)

 

Bruce

 

-----Original Message-----
From: Therion <therion-bounces at speleo.sk> On Behalf Of Tarquin Wilton-Jones via Therion
Sent: Monday, 27 May 2019 19:16
To: therion at speleo.sk
Cc: Tarquin Wilton-Jones <tarquin.wilton-jones at ntlworld.com>
Subject: Re: [Therion] Aligned cross sections for multiple passages

 

For anyone interested, I have documented my approach here:

 

 <https://therion.speleo.sk/wiki/multiplesections> https://therion.speleo.sk/wiki/multiplesections

 

Not that I have tested it extensively yet, so I may have to refine the "including it in your survey" part. I do plan to add some screenshots later, once I actually have used it for real.

 

If anyone has any suggestions for how to simplify or improve the process, please let me know :) _______________________________________________

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