From: Richard Knapp (gyp_caver_at_yahoo.com)
Date: Wed Jan 24 2001 - 22:26:02 CET
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>That's the cause of the infamous "RLUD question". LRUD is really
>assosiated with a station, not a shot, but left and right need a
>direction to be defined, so some information from a shot is needed. The
>eternal question is WHICH shot? The preceding shot, the next one, or
You could say without a shot or some other reference, LRUD is irrelevant. (Oohh can now I stop
recording it? ;-)
There are some things that need to be noted when taking passage dimensions.
- Where were the passage dimensions taken? This is more an issue for book people using a
"One Line" format instead of a "Two Line" format.
"One Line" format example
From To Dist Az Vert L R U D
A1 A2 10 22.3 -3.0 1 2 0 0.5
"Two Line" format example
Stat Dist Az Vert L R U D
A1 1 2 0 0.5
10 22.3 -3
A2 0 0.5 0 0.5
(note that this is some lovely passage!)
- What direction were the dimensions taken? Is this looking into the survey (to the next station) or
out of the survey (to the previous station)? Are the dimensions taken using the "average"
between the previous and next station?
- Are the dimensions taken from the station or the caver? They aren't necessarily in the same
place.
(for graphics, please see
www.geocities.com/richard_knapp/projects/css.html#data_file_walldimen)
>What if there is more than one shot to or from the station?
>What if there is less than one (The first station in the cave,
>a dead end, ...
This is one reason many people are now using the "Two Line" format instead of the "One Line".
CRF used to take LRUD at both From _and_ To stations. The To data was taken looking back to
the From. (FWIW, it was supposed to be used for early passage modeling information but it
never seemed to get entered.)
>If I was designing survey practice from scratch (I am not) I would have
>an aditional field in the book, direction in tens of degrees.
>"12/5/1/1/0" would mean left=5 right=1 up=1 down=0 when facing the
>direction 120 degrees (recording a third digit would make people feel a
>duty to measure it). Maybe SE/5/1/1/0 (to the nearest 45 degrees) is better.
Seems kind of overkill-ish. What counts is consistency in the measurements... and the abilty to
define the correct reference information.
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This archive was generated by hypermail 2b30 : Wed Feb 14 2001 - 00:03:53 CET