[Therion] Elevation scrap distortion with survex 3.d import

[wookey at wookware.org]

I am getting strange (and very annoying) results with a new survey.
This is my first real fully-digital project (using sexytopo/android) which
may be a factor.

So we have a ~1km cave system with two vertical entrances: Pollnatagha
'Natagha' and Pollpruglish 'Pruglish'.

Attached is a tarball of the current files:
(look at ee.pdf and natagha/blackarrow-ee.pdf to see what's broken.
You'll need to edit natagha/paris/paris.th and
natagha/blackarrow/blackarrow.th to process those two surveys on their own
(see below)

And underlying survex dataset, (which is all lovely and working nicely) is
here:
(I can't upload them somewhere sensible instead as 'the internet' here is
HTTP(s) only so no scp, ssh, imap, etc)

The fundamental issue is the plans are coming out fine, but the (extended)
elevations are severely distorted. After some hours staring at it last
night I worked out that the 'paris' survey was considered by therion to be
upside down so adding a '-flip vertical' to the scrap definition made
things look way better, and then making sure one leg was reversed took out
the rest of the distortion.

However this does not seem to work for blackarrow, which is all twisted
over itself, and not really any better if I flip vertically.

And the question remains - why does therion think my elevation sketches
are upside down? Is this actually a bug in the 'therion' export from
sexytopo? Or am I being dim about something? They look the right way up in
the therion editor.

I've spent quite a lot of time checking that the stations are numbered as
expected. I think there is something more significant about the extending
process, or possibly the import -surveys use process. (The log file note a
lot of 'unused fixed points' which are therion's made-up station numbers
for the survex data in the thTMPdir). Not sure if this is relevant or not.

Also, I've noticed that whilst I have the right 'import -surveys use'
runes for both the top level (whole cavesystem) and single-survey (paris).
If I leave them both in then a big distortion re-appears (stations 7,8,9
are moved ~30m along). What is going on there? Importing the same set of
stations twice should actually matter should it? (it would be nice to be
able to leave the 'single survey' import in place because then you can
check that alone without having to edit the 'singlesurvey.th' each time to
add/remove the import). The plan still works fine with the double-import.

I am currently in Northern Ireland with very limited internet (I've come
to the local show-cave visitor centre to send this), but will be back in
civilisation in Friday evg. If anyone replies to this today I'll be back
here about 5pm to check. I can't really draw up any more elevation at the
moment because I can't check it's not gone crazy (because it's already
crazy :-)

So the  structure is:
top-level NataghaPruglish.th (and thconfig)
with natagha and pruglish surveys.
I am using the 'import -surveys use' with corresponding empty therion
survey structure so that the individual scrap station names as just '1'
'2' etc.

There are about 12 surveys in total but you can ignore everything except
'paris' and 'blackarrow', two largely horizontal linear surveys under
'natagha'.

So this is now working:
import NataghaPruglish.3d -surveys use
survey natagha
 survey paris
 #import ../../NataghaPruglish.3d -surveys use -filter natagha.paris
 input "paris-ee.th2"
 endsurvey
endsurvey

But if you comment that 2nd filtered import back in (in natagha/paris.th)
then paris.7,8,9 move 30 to the right.

import NataghaPruglish.3d -surveys use
survey natagha
 survey paris
 import ../../NataghaPruglish.3d -surveys use -filter natagha.paris
 input "paris-ee.th2"
 endsurvey
endsurvey



If you have both paris and blackarrow input in natagha/natagha.th then you
get a different pair of large distortions (in ee.pdf) (plan.pdf is fine).

import NataghaPruglish.3d -surveys use
survey natagha
 survey paris
 #import ../../NataghaPruglish.3d -surveys use -filter natagha.paris
 input "paris-ee.th2"
 #import ../../NataghaPruglish.3d -surveys use -filter natagha.blackarrow
 input "blackarrow-ee.th2"
 endsurvey
endsurvey

One last question. If I wanted to try a projected elevation (to remove the
extra complexity of the extending process) how do I specify the projection
angle? An angle seems to be a parameter in a scrap '-proj elevation'
definition, but what determines what angle the _centreline_ is viewed
from? I cannot specify an angle in the top level 'export map' command:
export map -proj elevation -layout local -o "elv.pdf"

OK, there is a lot there - I hope I have explained it adequately, and that
someone can work out what on earth is going wrong here.

-- 
Wookey
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