As far as I can tell all New Zealand cave surveyors use the convention that the lrud data refers to the ‘from’ station (unlike Therion).

Mostly because the preprinted survey paper pads we use lead people to this way of doing it.

When learning to use Therion I pretty quickly moved to the solution 2) suggested by Martin below. 

The advantage is that users are certain about which station the lrud applies to, and the amount of potentially confusing data on each line is reduced. 

The disadvantage is that when there are multiple legs from each station, Therion does not know which leg to apply the lrud to.

Personally I am happy with this limitation, however a ‘lrud-station [to|from]’ statement  would provide some flexibility and clarity without the need for new users to refer to The Therion Book quite so much.

Bruce

---

From: therion-bounces@speleo.sk [mailto:therion-bounces@speleo.sk] On Behalf Of Niklas Konstenius
Sent: Saturday, 23 July 2011 10:43 p.m.
To: List for Therion users
Subject: Re: [Therion] Odd behavior exporting map using LRUD's

> 1. use [from to] syntax:

Thanks for the tip. This method however forces us to write the LRUD measurements in the data files twice. This redundancy in the data is not a good thing as I see it.

It would be very nice if therion could have an option to define which station the LRUD's belongs to. For example:

centerline

lrud-station from

data normal from  to  length  compass  clino left right up down

a  b  10 90 0 2 0 2 0

b  c  10 90 0 0 2 2 0 

c  d  10 90 0 2 0 2 0

endcenterline

Or is it so uncommon to get LRUD from the FROM station that this functionality is not needed?

/niklas

On 23 July 2011 08:21, Martin Sluka <martinsluka@mac.com> wrote:

On 23.7.2011, at 1:10, Niklas Konstenius wrote:

       a  b  10 90 0 2 0 2 0
       b  c  10 90 0 0 2 2 0
       c  d  10 90 0 2 0 2 0
endcenterline
-----
Since LRUD is measured at from-station this data indicates that station a and c is positiond at the right cave wall and station b is positioned at the left wall (station d is undefined).

Therion in this case use LRUD on TO station - default behavior.

If you need LRUD on FROM station you may:

1. use [from to] syntax:

data normal from  to  length  compass  clino left right up down

   a b 10 90 0 [2 0] [0 2] [2 2] [0 0]
   b c 10 90 0 [0 2] [2 0] [2 2] [0 0]

2. station left right up down

data normal from  to  length  compass  clino

       a  b  10 90 0

       b  c  10 90 0

       c  d  10 90 0

station left right up down

      a 2 0 2 0

       b 0 2 2 0

       c 2 0 2 0

m.
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