â¦so to clarify further â¦
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:[email protected]] 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 âvthresholdâ.
>From the Therion Bookâ¦
â
vthreshold <number> <units> â 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 â 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
â
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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