[Therion] Elevation Projected Direction? (and creation from Extended Elevations)

Bruce Mutton bruce.mutton at paradise.net.nz
Wed Dec 12 21:39:58 CET 2007


I seem to have acquired more of a Therion mindset, and drawing plans is
going quite well.

Just trying to get the elevations sorted, and perhaps I'm trying too much at


Using Therion 0.5.2.

Have roughed up an extended elevation based on a scanned sketch (of a
projected elevation - the passage runs more or less from north to south, and
descends at about 30 deg, as surveyed).  


I notice I had to add an 'extend left' to the centreline data to stop the
passage plotting upside down and sort of inside out. (although interior of
passage was correctly rendered) I assume that this approach is the correct
way to address this issue??


The extended elevation looks more or less OK, vertical lines a little
slanting, no doubt due to the distortion caused by foreshortening as the
survey legs range diagonally from side to side across the wide passage.  I
guess I should adjust my survey technique!

The code below produces the map.


export map   -projection extended  -layout ThisCaveMapLayout \

  -output ./Maps/SystemExtendedElev.pdf  -fmt pdf


Now here's where I thought I'd cheat, to get a projected elevation from the
same sketch.

I copied my extended elevation.th2 file and renamed it projected
elevation.th2, then edited it to change the scrap name and projection type
from extended to elevation.  (It's not too different in concept to redrawing
it manually in another file, where the passage is fairly straight and runs
perpendicular to the desired projection direction)


The trouble is, this always plots as though it is extended (dashed
horizontal grid, no vertical grids) but with an obvious projection (of 000
deg- assuming 0 deg means looking towards the north(?)) that does not change
regardless of the bearing provided in the export command.  In other words
it's partially working. For example the code I used is below.


export map   -projection [elevation 270 deg]  -layout ThisCaveMapLayout \

  -output ./Maps/SystemElev.pdf  -fmt pdf 


(I have tried similar code for single surveys, individual caves and cave
system levels of detail with the same result)


These lines are all in the same thconfig file, and I had a few issues with
map structure as interpreted by the Therion compiler window, until I
realised that Therion seems to determine the hierarchy based in part on the
map titles.  Duplicate map titles seem to create trouble!


I realise there is not enough information here to properly assess, but is
there something fundamental I'm doing wrong?  When I just had centreline
data the projected elevations seemed to work OK for any direction.


Any hints or comments appreciated.


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