[Therion] FW: Doubt about vertical sections

[Bruce]

…so to clarify further …

As the gradient of a survey shot increases, therion switches from the assumption that passages are measured LRUD (vertical up down) to an assumption that they are measured LR-front-back (up down perpendicular to the passage orientation) and then at +-90 deg to the assumption that they are measured NSEW.

 

You can control the inclination at which the first change occurs by adding

 

    vthreshold 40 degrees 

 

to your centerline block of data.

 

Unfortunately we cannot change the NSEW behaviour (yet).

What you need to know of course, is approach the surveyors took when they were collecting the data, and adjust your input accordinly.

 

Bruce

 

  _____  

From: therion-bounces at speleo.sk [mailto:therion-bounces at speleo.sk] On Behalf Of Bruce
Sent: Thursday, 1 November 2012 7:08 a.m.
To: 'List for Therion users'
Subject: Re: [Therion] Doubt about vertical sections

 

Marco

I tested your example and got the result you described with both xvi and pdf outputs.

 

I think you have found the transition defined by ‘vthreshold’.

>From the Therion Book…

“

vthreshold <number> <units> ◃ threshold for interpreting LRUD readings as left-right-front-back reading perpendicular to the shot.

If passeges are horizontal (inclination < vthreshold), LR is perpendicular to the shot and UD is vertical.

If passages are more or less vertical (inclination > vthreshold), even UD becomes perpendicular to the shot – otherwise passages would not look very good. In the case of vertical shots, UD is interpreted as north-south dimension from the station to allow tube-like modelling of verticals

“

I had thought the default value of vthreshold was 60 degrees, but it seems it may be around 67.5 degrees.

 

Bruce

 

 

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