[Therion] Making projected elevations

[Bruce Mutton]

Hi Tarquin
Probably better to create a new post for each topic.  Makes for smaller bites and easier to respond to.

Basically, there is no conversion of sketches from one projection to another.  You have to do the work yourself or accept any distortions that a fudge might incur.
Have a search on the mail archive for 'projected elevation'. In essence I think you have come to the right conclusions below.
https://www.mail-archive.com/therion@speleo.sk/
Check out https://www.mail-archive.com/therion@speleo.sk/msg06370.html and https://www.mail-archive.com/therion@speleo.sk/msg06368.html

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).
Your description of the cave/mine makes it sound perfect for an extended elevation to me, especially as you already have extended sketches.

Multiple projections on the same pdf page can only be achieved using map-image to insert them as images.  Or you could post-process with another application (which defeats a key advantage of Therion).
You could take your extended sketches and just flag them as projected, accepting that there may be gross distortions.
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.

Bruce

-----Original Message-----
From: Therion <therion-bounces at speleo.sk> On Behalf Of Tarquin Wilton-Jones via Therion
Sent: Thursday, 25 April 2019 09:56
To: therion at speleo.sk
Cc: Tarquin Wilton-Jones <tarquin.wilton-jones at ntlworld.com>
Subject: [Therion] Making projected elevations, and using map connectors

Hi,

Still learning (never stop)...

I have looked through the various tutorials, and several examples, but I have not found any information on how to create a projected elevation - all tutorials stop at that point with "TODO: show how to do elevations".
The software I am using to survey the caves (DistoX2 + SexyTopo) gives me a plan view and an extended elevation, exported as centreline+xvi.
The area I am surveying is mostly linear with passages stacked at various levels above each other. As a result, projected elevation is more useful than extended elevation.

I know I have to use "-projection [elevation 265]" on my scraps and maps to make them all work when I try to use:
export map -projection [elevation 265]

However, I have not been able to find how to get from an extended elevation to a projected elevation. I had hoped for some magic where I just create an extended elevation then ask Therion to warp that extended elevation into a projected elevation, but I have come to the conclusion that I probably have to do this:

export map -projection [elevation 265] -output elevation265.xvi

Then create a dedicated surveyname_elevation265.th2 file and go over all the survey data and create the required scraps for it, without being able to see the sketches in the XTherion scrap editor.

Have I made the right assumption, or is there some clever magic that can happen? Does this mean that in order to create two elevations, one facing 265° and one facing 180°, I actually have to do this all twice, creating each scrap from scratch each time?

Imagine I want to have half of the cave on a bearing of 265 and the other half on a bearing of 180 in the same file (because the cave turns a corner half way along) - essentially extending a projected elevation.
I could export the data once on a bearing of 265, and once on a bearing of 180, then create appropriate scraps for each half, pretend that the ones on a bearing of 100 are actually on a bearing of 265 by using the -projection options of maps and scraps. But then it would warp them to oblivion when trying to make it fit the centreline. So would I actually have to export two PDFs, one with a map that only covers half of the cave on a bearing of 265, and another that covers the other half of the cave on a bearing of 180, and position the outputs very close together by importing them as images into a third map?

(Not as insane as it sounds. It is a mine, with major passages all very linear at different levels, and just one significant passage running at right angles to the other passages.)

... snipped...
Tarquin
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