Bedding planes, rose diagrams and bug fix

[Phil Underwood]

Wooks sent this to me, but he wanted to go on the list as well, so I'm
forwading it...

 ----------  Forwarded Message  ----------
Subject: Re: Bedding planes, rose diagrams and bug fix
Date: Tue, 2 May 2000 13:57:58 +0100 (BST)
From: Wookey <wookey@aleph1.co.uk>


On Tue 02 May, Phil Underwood wrote:
> I'm thinking about making a couple of analysis tools for survex/chasm.
> One is a rose diagram -

> Do people think that these kind of widgets are a good idea, or just
> pointless bells and whistles=20

Generally the latter, but some analysis tools can be useful.
Rose diagrams look nice, and might be useful to some people, but on the
whole I have never had one, nor wanted one. Their functionality is
limited by the way surveys zig-zag down passages, so the survey legs
characteristic of a particular passage direction are actually ones at say
20 degrees to the direction of the passage. For a very regular
south-trending passage surveyed regularly you get a rose diag with no
legs at 180 degs, and two peaks at 165 and 195 degrees, which is a bit
misleading at best. So, on the whole I think rose diags are pretty but
largely useless. However some surveyors may think they are great and use
them all the time?

> The other thing I'm currently thinking about is a gadget that will
> search through the legs in a survey, looking for any planes whcih seem
> to contain a lot of legs eg a phreatic level or a fault controlling the
> cave formation.

This is potentially a more useful idea, although on the whole, people
looking at plots are very good at this sort of thing - is there really
any point trying to do automatic analysis? the 'planes' have the same
deviation problem associated with them as the rose diags.

The tools I _do_ want are:

1) display indicator of entrances. (hmm, that's not really analysis is
it, but it would be _really_ useful)

2) easy-to-use 'distance between points' system. The caverot scale bar is
OK, but it's often inconvenient having to drag the cave over to the
bottom left and spin it to line up the relevant point with the scale bar.=
=20

A scale bar I can move to the middle/rotate would be a good start, but a
'distance between two stations' feature would probably be better. The
advantage of the scale-bar approach is that you don't have to have
stations at the points you want to measure. 'Tenths' ticks on the scale
bar would be really helpful too (that's probably incredibly easy isn't
it?).

Maybe aven already has these? Oh how I wish I could compile all these new
versions :-(... [last attempt told me that gtk was missing a load of Xlib
headers which presumably means I need X-devel package(s). It's such a lon=
g
CD/download chain to get anywhere if you don't start from the right
place....]

3) ability to get pos data (esp entrances) from display. Option to
display depth-only useful too for doing elevations. Even better would be
a way to generate a list of stations for which I want the depths printing
out. So I get out a nice list of station: depth ready for sticking on the
survey. Need to be able to add adjustments (to account for stations not
at floor/surface level). Or a constant offset if they need to be reletive
to some datum other than whatever the cave is plotted at. Outputting=20
TeX/LateX/rtf file for printing might be best?

Wookey
--=20
Aleph One Ltd, Bottisham, CAMBRIDGE, CB5 9BA, UK  Tel (00 44) 1223 811679
work: http://www.aleph1.co.uk/     play: http://www.chaos.org.uk/~wookey/
-------------------------------------------------------

--=20
Phil Underwood <furbrain@furbrain.screaming.net>
Homepage: http://members.xoom.com/bighairyone/
"It's not what you've got, it's how you make it explode."