[Therion] Training Course Guide for Therion from the UK CaveSurveying Group

Bruce bruce at tomo.co.nz
Thu Jun 14 10:07:55 CEST 2012


>The training course and example data can be found here:
>http://cp.cavesurveying.org.uk/index.php/articles/3-therion-tutorial

>I would welcome any feedback on the content of the tutorial as it is
>an on going project ...

I have a question for the Therion Gods.

I notice the example uses a data format with the map definition INSIDE the
survey like this...

survey bpw
	input bpw.th2

	map bpwMP
  		bpwSP1
  		break
 		 bpwSP2
	endmap

	centreline
  		date 2011.12.03
  		<etc>
	endcentreline
endsurvey

I have always tried to keep my map definitions OUTSIDE of surveys, as I've
been following the dictum to keep surveys and maps as independent as
possible.  Having said that, Therion seems to think my maps are inside the
survey one level up in the hierarchy, for example I need to specify items
like;
select bpwMP at BullPotFarm

(assuming, hypothetically that the example project is developed to include a
few more caves, and collects them into survey called BullPotFarm),

instead of just 

select bpwMP

which is what I normally get for a single level survey like the one in the
example.

It has always confused me a little, as there seems to be no reason, based on
my inputs, that the maps should be part of any survey.  Theoretically they
should be a completely independent hierarchy (I think).  And the Xtherion
map structure window places them in their own hierarchy (independent of
surveys), but in the lower levels therion puts them in a survey like
@BullPotFarm when it is double clicked to produce a 'select' statement.
Everything compiles fine, so I just accept it and put it down to one of
life's little mysteries.

So enlighten me.  Is Footlegs example with the map defined within a survey
the preferred way to define maps?  (because therion will force them into a
survey if you have more than one level of surveys anyway?)
Or are there more ways to do things, with various pros and cons? 
Bruce





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