[Therion] Making projected elevations

[Tarquin Wilton-Jones]

Hi Bruce,

A most helpful reply, as always.

Since it seems I am not totally insane, it would be good to get this
somewhere easier to find, such as a wiki page. Having never edited the
Therion wiki, what is the convention there - it usually looks like one
page per jumble of knowledge someone tries to impart (with a meaningless
URL), rather than a single page per topic. Any suggestions for where to
create the page to store this information?

> I started my Therion life as a projected elevation fan, but now I think extended is the way to go (subject to the proviso that they are way more vexatious for a non-trivial cave).


<aside title="In support of projections">

In most cases where we would use elevations - potholes, for example -
extended is most certainly the best way, since it moves everything out
of the way. Once you tweak everything to make it all make sense.

In this case though, the relationships between the levels and/or surface
is the main thing of interest; where you see an aven (rise/stope) in the
lower level, and exactly where that is likely to meet a pile of boulders
in the level above. Or when a passage sits directly below a surface
shaft. Extended elevations, while you can use them for navigation,
destroy the relationship between the different levels. Unless you put in
a tonne of work to twist them back into alignment (destroying the
purpose of an extended elevation).

Projected definitely hurts when passages run parallel to each other or
meander towards the viewer, but that only happens once in our entire
system, and only for an unimportant part of it. It is an extremely
linear system.

Obviously, each approach has its benefits. But in this case, our team
prefers projected. I was mainly checking to make sure I wasn't going to
put in loads of effort to draw the projected and extended separately,
only to have someone say "you could have done that automatically". But
you have confirmed that separately is the way to go anyway.

</aside>

> Multiple projections on the same pdf page can only be achieved using map-image to insert them as images.


OK, should be simple enough. It could be done with "continues from here"
slashes, similarly to  how Cuthbert's was done.

> You could forget about the xvi file, and print out a projected centreline (one trip file at a time is my preference), and sketch on that the passage detail, scan it, and import it as a background image in XTherion.  Then you trace it with XTherion to produce scraps.  Seems odd to take an electronic process, and force a pencil and paper stage to it, but that is my preference if the alternative is to have an xvi with no sketches embedded.


Very nice, thanks for the tip. Pencils still have a place.

Cheers,

Tarquin