Bedding planes, rose diagrams and bug fix

[Phil Underwood]

On Tue, 02 May 2000, you wrote:
>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 sa=
y
>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?

Depends on the way you survey - I've found that on some surveys, it seems=
 a
pretty accurate description of the general trend of the passageway.
>
>> 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 th=
e
>> 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.

Not so sure about this one - there may be ways around the deviation. If t=
he
analysis tool is designed so that it accepts a certain degree of error in
the readings, these deviations may "average out". Best way would be to
write the software, and see how it copes with real data.

>
>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)
>
But we need then to have a command like *entrance <station> to define an
entrance, and this needs to be transferred to the 3dx file somehow.

If you *fix all the entrances, I'd be able to make chasm display marks ne=
xt
to fixed stations.
Any ideas what symbol you'd want to use here - what about #p161 instead o=
f
\p161, next to a cross marking the location?


>2) easy-to-use 'distance between points' system. The caverot scale bar i=
s
>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=
=2E=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?).
Tickmarks on the scalebar will go in the next release - very easy.
The distance between two points bit should also be pretty easy - I'll put
that in my TODO list.
>
>Maybe aven already has these? Oh how I wish I could compile all these ne=
w
>versions :-(... [last attempt told me that gtk was missing a load of Xli=
b
>headers which presumably means I need X-devel package(s). It's such a lo=
ng
>CD/download chain to get anywhere if you don't start from the right
>place....]
Would an rpm help? - I'm willing to fettle one up so that all you need is
the rpm, and the relevant gtk libs. i386 only, I'm afraid.

>
>3) ability to get pos data (esp entrances) from display.=20
Already available in chasm - station window displays the Northing, Eastin=
g
and altitude/depth of the selected point.=20

>Option to display depth-only useful too for doing elevations.=20
I could put this in the status bar at the bottom fairly easily.

>Even better would be=20
>a way to generate a list of stations for which Iwant the depths printing=
=20
>out. So I get out a nice list of station: depth ready for sticking on th=
e
>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 reletiv=
e
>to some datum other than whatever the cave is plotted at. Outputting=20
>TeX/LateX/rtf file for printing might be best?=20
A list of stations to produce a file with positions would be possible wit=
h
a little work.  Constant offset is possible, but comparative adjustments
will be very hard - you might as well put the data in later.
I'd prefer to output plain ASCII (maybe tab-delimited)- much more portabl=
e,
and you can cut and paste more happily into other apps. And of course,
ASCII is easy, and I don't understand TeX too well.

--=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."