[Therion] Extended elevations - development snapshot (commit 6860f82).

[Bruce Mutton]

Thanks Stacho

This is much appreciated.  Might take me a while to work through testing it.

 

Regarding ‘extend <number>’, can this be used as ‘extend <number> [<station> | <leg>]’?

Or can it only be used in-line with the survey data? Or can it apply to groups of extend statements defined in a block separate to the survey data?

 

Just starting to compare before and after (extend splay and loop bugs resolution) by looking through my datasets.

A sample of one with no loops suggests the splay fix is good, or at least credible.

A sample of one other with some loops that caused me pain when originally drawn, suggests that the difficult loops may have remained unchanged, but there is at least one unexpected change as illustrated below.  There is an unexpected and unwanted display of station 6.3

 

The extend control for this part of the cave follows.





This is how Aven interprets the loops (shown in (projected) elevation) ie a loop within a loop within a loop.

Curious how Aven does not seem to recognise the two ignored legs within the loop, as being within a loop ie they are coloured grey, and not blue to reflect the std deviation of the closure error.



 

Therion original incorrect extended splay behaviour



New Therion 5.5.1+9860f82 splay behaviour



PocketTopo extended drawing and splays



PocketTopo drawn and TopParser generated xvi on which above drawings are based



 

Station 6.15 has the same map-connection line in each Therion export, but station 6.3 pops up with a spurious map-connection in 6860f82.

Notice how the xvi splays are different in all of the above.  It has long been my suspicion that each application produces quite different extended splay interpretations, so I am not surprised or necessarily troubled by this.

When drawing in a cave I often think that PocketTopo gets it quite wrong (and it changes splays dynamically when the next leg is surveyed – which is disturbing at the time, but is adhering to the paradigm whereby splays are allocated to the leg with the closest bearing).

It looks like the new Therion 6860f82 extended splays are quite similar to PocketTopo but not so much like the xvi.  I presume the xvi is incorrect.

 

Bruce

 

From: Therion <therion-bounces at speleo.sk> On Behalf Of Stacho Mudrak
Sent: Thursday, 30 July 2020 22:45
To: List for Therion users <therion at speleo.sk>
Subject: Re: [Therion] Splays - Revisiting Breaking extended elevations

 

I have tried to fix all the extended elevation issues in the latest development snapshot (commit 6860f82 <https://github.com/therion/therion/commit/6860f82e616edb5e0fc7b35120cfc68eb682897a> ).

 

1. splay shots should be extended relatively to survey shot with closest (horizontal) bearing

 

2. there is a possibility to specify reduction ratio for extended elevation (0 = vertical, 100 = normal left/right) - just use "extend <number>"

 

3. extend ignore via path of 3 points should now work -- use "extend ignore <s1> <s2> <s3>". I think this should allow all crazy loop configurations to be solved, but I am not still 100% sure.

 

Unfortunately (but not surprisingly :/), there was a bug with the extended elevation algorithm. In the case there were loops present in the centerline, it caused some random behaviour.

 

I have tried to fix this bug, but it required quite a deep change to the code. My data seems to work, but I suppose, there may be some cases when it still can fail. Could you please try your datasets?

 

Thanks, S

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