[Therion] Detecting errors

[Bruce Mutton]

OK, I found it.

Therion stores it in the thTMPDIR folder, which can be preserved if one
follows the guidance here 

https://therion.speleo.sk/wiki/metapost#how_to_get_therions_metapost_code_an
d_tex_code

 

Survex loop closure seems to be fed arbitrary station names (no survey
structure) by Therion, but you can kind of work it out if you open the .3d
file with Aven.  A bit daunting with 35000 stations though.  I found that I
can right-click the data.err file, and sort its contents by various error
metrics.

 

This is pretty cool, and highlights just how embarrassingly bad some of our
early pre-disto loop closures were.

It is a tool that gives some hope of systematically debugging and solving
possible locations of the bad data, or highlighting passages for possible
resurvey.

 

I guess Survex users have always known of this functionality, but it adds a
new dimension for this Therion user. 

 

Bruce

 

+

 

 

-----Original Message-----
From: Olly Betts <olly at survex.com> 
Sent: Tuesday, 20 August 2019 11:27
To: Bruce Mutton <bruce at tomo.co.nz>
Cc: 'List for Therion users' <therion at speleo.sk>
Subject: Re: [Therion] Detecting errors

 

On Fri, Aug 16, 2019 at 02:23:20PM +1200, Bruce Mutton wrote:

> I'm a Therion user (not Survex), although I use survex loop closure.

> That gives some additional statistics in the Therion log file, but not 

> the loop error standard deviations.  I wonder if Therion (or Cavern) 

> could incorporate these in the log file, or if Aven could be made to 

> list them?

 

Cavern already produces such a file - that's exactly what the .err file I'm
referring to here tells you:

 

> > 76.brave.18 - 76.brave.17 - 76.brave.16 - 76.brave.15 - 76.brave.14 -
76.brave.13 - 76.brave.12 - 76.brave.11 - 76.brave.10

> > Original length  32.35m (  8 legs), moved   1.26m ( 0.16m/leg). Error
3.90%

> > 4.920289

> > H: 5.888476 V: 0.864600

 

I'm not sure what happens to that file when therion calls cavern to process
data though.  I keep my survey data in .svx files and process as a separate
step, then point therion at the .3d file.

 

Cheers,

    Olly

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