[Therion] Map Definitions discussion

[Bruce Mutton]

Here is a conversation that Nick and I had recently, about using map
definitions.

Bruce

 

From: Nick Bairstow  
Sent: Saturday, 5 May 2018 12:03 AM
To: Bruce Mutton  
Subject: RE: Map Definitions

 

Bruce, thanks for that explanation, I now think I understand things a little
better. You descriptions are once again very clear and understandable. I
will grab some data next week and play around with the various scenarios.

 

I do appreciate your spending time to give advice it is a great help.

 

Cheers,

Nick

 

From: Bruce Mutton
Sent: 03 May 2018 21:03
To: Nick Bairstow  
Subject: Map Definitions

 

Hi Nick

Yes, your folder structure seems normal and appropriate.

 

Believe it or not (my understanding is that) Therion is designed to
automatically produce the 'best' pdf output that it can, based on what has
been input, with minimal effort on the users part.  

But if the user wants to have more control, then they can (I always want .).

That control starts in a thconfig file with the choice to 'select' 'surveys'
and or 'maps' for output.

Then extends to defining 'maps' that can contain either surveys, scraps or
other maps.  Usually you don't include surveys, except that personally I
prefer to while I am progressing through the drawing process**.

 

Have a look at this page https://therion.speleo.sk/wiki/bds#concepts  and
scroll down a bit.

 

"select selects particular surveys and or maps to export. If you do not
select a survey, all surveys are selected by default. If you do not select a
map, all scraps and maps are selected by default. Optional. "

 

This explains why, with no maps defined or no maps selected, you get
everything that you have drawn.  You should also notice that if you have no
scraps drawn, your default output will have all of the cave centrelines
present.  As soon as you have one scrap, centrelines vanish from the output,
and you only get your scrap.

 

If by chance you want to produce an output with only some of what you have
drawn (at and below the current level of hierarchy), or you want to offset
parts of the drawing, then you MUST define maps, and select them for output
appropriately.

 

Also, if you want to see a combination of scrap drawing AND CENTRELINE
outside of the drawn scraps extent, or with splays visible, then you must
include the relevant surveys in map definitions.  See my ** comment above.

 

Survey and map definitions also give you control over the title that appears
on the drawing.

It can be complicated, but I once figured it out, and made this bit of code
to put in layouts used for plan outputs.  I prefer to allow Therion to
decide the output title based on the information I have entered in surveys,
maps and selections, but sometimes an override is required.  Note that
Therion assumes a survey or map title is the same as its id, unless you
specify -title "name" to override the id.  My preference is to always give
surveys or maps likely to be a primary selection for output a title that I
would like to see on a finished pdf output (and use a concise id).

The code, as below, only has effect if due to the users choices, Therion
cannot deduce a unique name for the output.

 

 

   #PLAN Cave Map Details

  #--------------------

  # Define Map title overrides    

    code tex-map

   % Output map title as determined by Therion 5.3 is stored in cavename. 

   % It will be empty if there are multiple maps selected for any one
projection

   % AND there are multiple source surveys identified in the thconfig file 

   % ie Therion can not infer a unique title from the input data given.

   % This code allows you to define an output map title {cavename} if it
happens to be empty

   

  \edef\temp{\the\cavename}        % cavename from Therion   

  \edef\nostring{}                 % empty string 

  \ifx\temp\nostring             % test if cavename is empty

        % if empty reassign cavename to describe selected maps as a group

 

                                \cavename={Project Area Caves} 

                                

  \else % if not empty keep the value set by therion, or assign an override
cavename here

  \fi

endcode  

 

This page on  what input data Therion draws on to produce outputs may well
be cryptic, but the bottom rows in the table may help.  It is based on my
deductions and experiments only.

https://therion.speleo.sk/wiki/exportselectionformat

 

 

Hope this helps. Good luck

Bruce

 

 

From: Nick Bairstow  
Sent: Friday, 4 May 2018 3:19 AM
To: Bruce Mutton  
Subject: Map Definitions

 

 

Hi Bruce, as I am supposed to be tutoring folk in Therion I thought it wise
to clear up some of "my" questions. I see in the mailing list you have
spoken about this over the years so maybe you can help.

I have a cave that has been surveyed with a total of 6 separate surveys.
i.e. I have 6 topo files. I process each topo file though TopParser and the
outputs file fly off into their relevant folders in the hierarchy. 

 

MainCaveName

                Survey1

                             Survey1.th

                             Survey1.th2

                             Thconfig

                             Pocket Topo folder

                Survey2

                Survey3 etc.

 

Also in MainCaveName folder I tend to put:-

                Output

                            Survey1Output

                            Survey2Output etc.

                Index.th

                thconfig 

 

Nothing unusual and I think a quite normal structure which works well for
me.

My question is in the index.th I have always used a map definition but I
notice if I do not use one I still get the same output.  As long as I have
in the index.th, as in this case:-

 

input Survey1/Survey1.th

input Survey2/Survey2.th etc.

 

I get the same result. After reading all I can find I am still confused. I
suppose I am making quite straight forward maps so maybe it does not matter
which way I do it. What situation would require me to use a map definition
in the index or should I use one all the time? I have various idea's as to
how/why I do this but I am just not clear. Also looking in our UK BCA data
archive which I find really useful for help I see both methods are used so I
think I'm not the only one confused.

I think this subject warrants a really simple wiki article, once I fully
understand it I may have a go at one.

 

Cheers,

Nick

 

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