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

[alastair gott]

Hi Wookey,

Quick reply.

Looks like you might need to close the walls off, maybe add a wall invisible on the end of some of those walls, without looking deeper into your data if you’ve got scrap joins then open wall ends will always try and join back where they can.

This also goes for big pots open to the surface, where the walls will be bent down to nearest wall to join to. Add a wall invisible to the “top” of the cave and you’ll be sorted.

Al.

Sent from my iPhone

> On 25 Aug 2021, at 13:43, "wookey at wookware.org" <wookey at wookware.org> wrote:
> 
> 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
> <NataghaPruglish.tar.gz>
> <NataghaPruglish-survex.tar.gz>
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