>One of the things I struggle with as a new user of Therion is the documentation. In this case I found nothing about projected elevations in any examples of on the wiki.

I also learned how to do elevations (and many other things) based on answers from this forum.  For better or worse I have figured it is up to the beginners who are struggling (me quite a lot of the time) and the users who have some insight (me sometimes) to write the instructions and make corrections in the wiki.  They are likely to better know the needs of those who are trying to learn.  I’d rather the therion authors continue to put their time into therion authoring!  There are still many features that need fixing and implementing before therion could be called a mature project (even if it is leading the pack in my opinion).  Agree the therion book is lacking a bit of clarity on projected elevations.

>I am happy to write a general introduction/walk through and provide an example project for the wiki if someone can set me up with an account to allow me to edit wiki pages.

Excellent. See the contacts on http://mailman.speleo.sk/mailman/listinfo/therion for access.
http://therion.speleo.sk/wiki/doku.php?id=tbe and http://therion.speleo.sk/wiki/doku.php?id=tfc would be a good place to insert such and example if I can invite you to edit someone elses page J  (You are welcome to edit my pages if you think it’s better there http://therion.speleo.sk/wiki/doku.php?id=do)
I have the wiki open and refer directly to it most times when I’m drawing more than just a small amount.

>I do wonder why if I am declaring everything in the map / endmap block in the th file, and I give that map a name there, then why is it not possible to specify that map by name in the thconfig file export, rather than have to repeat the map type information and have therion try to work out what map from my th file to use to generate that pdf? Just a suggestion.

Good question.  The sort where I learn by researching the answer. I guess the answer is that the ‘source’, ‘select’ and ‘export’ statements are distinct from each other.
When it comes to exporting you are really just saying what type of output you want, and what its name will be, and which layout options to use.  As far as which maps to export goes, that is chosen with the select statement. A mistake that I often made was to think that ‘elevation’ was a single projection, when in fact it could be any of 360 or so projections (if we think in degrees).

Your example is a simple one where you have specified a source file that only has a few maps and sources (one each possibly) and you have selected no maps (so by default all maps are selected).
I have a cave system with three caves and lots of surface features, and so except at the bottom of the hierarchy my thconfig will have a source for the caves, a source for the surface dem and a source for the surface features and minor caves.  Then I will have multiple selects that have all of the commonly chosen maps that I may create at this level.  These may have all sorts of projections, not necessarily the same for each cave or part cave.

Now come the exports.  Those that are exporting to map or atlas only need to choose the projection and all the ‘map objects’ previously selected will be included in the output.  One export statement can therefore produce a combination of many maps (with each map having it’s own layer in the pdf – nice).

So I think the answer to your question might be… for the simple case, yes you have to specify the projection three times, but for the more realistic case of a larger cave, you can select many maps, and filter what you get by using the export statement without having to get too carried away with commenting/uncommenting select statements.

This might have confused more than helped.  Maybe soon I’ll add my thconfig template to http://therion.speleo.sk/wiki/doku.php?id=templates and that might help some.  I still have no idea if I am setting out my therion data in a sensible way, but it does seem to work out OK.  I’m still on the lookout for other ways to do it.

Bruce