[Therion] Joining maps with the join command

[Tarquin Wilton-Jones]

Hi Bruce,

> But looking at your original post, I think maybe you have a join inside
> a map definition.

Oh my goodness. Nail on the head, sir! I owe you one. My command was
already correct (after Benedikt explained that scraps do not belong to a
map, and to reference the scrap as a child of its survey), I just put it
in the wrong place. Failed to recognise the context options for the command.

For anyone else who finds this thread while looking for help, this is a
summary:

Both the line/point IDs and the scrap IDs can be referenced within the
survey where they are created/imported. You can either tell it to
automatically connect the best fitting points of the scraps (with the
optional -count parameter to tell it how many passage ends join with the
other scraps). Or you can manually select each linepoint in one scrap
that should connect with which linepoint in another scrap.

cave1.th:
survey cave1
 input "cave1 plan.th2"
 input "cave1 ee.th2"
 map cave1MP
  scrap1
  scrap2
 endmap
 centreline
  ...
 endcentreline
endsurvey

cave2.th:
survey cave2
 input "cave2 plan.th2"
 input "cave2 ee.th2"
 map cave2MP
  scrapa
  scrapb
 endmap
 centreline
  ...
 endcentreline
endsurvey

Then I have an overall file which combines the maps called allcaves.th:
survey allcaves
 input "cave1.th"
 input "cave2.th"
 map allcavesMP
  cave1MP at cave1
  cave2MP at cave2
 endmap
 #either
 join scrap1 at cave1 scrapb at cave2 -smooth on -count 1
 #or
 join line1 at cave1:end line3 at cave2:0 -smooth on
 join line2 at cave1:0 line4 at cave2:end -smooth on
 centreline
  ...
 endcentreline
endsurvey

Another survey that uses "input allcaves" could also use one of these to
reference the scrap or linepoint within the child "allcaves" survey:
scrap1 at cave1.allcaves
line1 at cave1.allcaves:end

<aside>

I do wish these error messages were a little more informative, pointing
out where you made a mistake, but I am so glad it was something so
simple. Does it actually not know what the problem is? Rather than
saying "you put it in the wrong place" it says "the map item is not
valid", which makes me assume a syntax error rather than a command
hierarchy error.

(My favourite error is the one where I forget to click on some survey
stations when defining a scrap, and it tells me "this map is too large,
and you need to pick a smaller scale". Or the one where I click on a
station that was already defined in another scrap, and it fails to put
the right -name in the options - or it just picks the "next" station
number which was not the right one. Same error message. Or some random
code dumps about it failing to find the largest coordinate when closing
lines. These messages are ... "fun".)

</aside>

Many thanks to you all for the advice (and to Martin for offering to
help debug). It seems that I have it working well enough now.

Cheers!

Tarquin