[Therion] Multiple elevation maps

[Bruce]

      Ben

>It seems I am still missing something.  The trivial example PracticeCave 

compiles correctly and produces two unique elevation PDF files.  However, it
is not working on my real cave.

 

>I changed all the elevation scraps to "projection elevation".  I put each
in 

its own map statement, then used a select statement before each export.
This 

produces two identical PDF files which contain BOTH of the elevation maps.

 

      That is because each export statement exports all maps of the
specified (or implied) projection.

      You made them all the same (elevation, which as I mentioned is a
default or proxy for [elevation 0 deg] or 'looking north')

 

>So then I added a view angle to all of the elevation scraps (two different 

angles) and modified the export command to use the same view angle.  Now I
get 

an error:

 

>therion: error -- MillCreekCave.th [41] -- incompatible scrap projection --
Elevation1

 

      Each export has an explicit or implied projection, and it can ONLY
include maps that have the same projection.  Likewise, each map can ONLY
contain scraps with matching projections.

 

>Could there be something in the join statements that is not right?  Each of


the two profiles in this cave has multiple scraps.  I have to separate sets
of 

join statements to bring them together.  It is almost like Therion is trying


to join ALL of the elevation scraps rather than just the ones I specify.

 

      No. Nothing wrong with join, although join does add an extra layer of
complexity when you are trying to debug problems, because the morphing
disguises other things that may be going on.  It is more likely a poor
choice of projection view angle.  From your earlier post (below) it sounds
like you have extended profiles, so if your projected elevation angle looks
'end on' to the passage you will get a real mess.

 

 

>There is a new question ...  What is the effect of specifying the degree
angle of the view for "-proj elevation"?  

 

      Search for 'projection' in the Therion wiki FAQ for explanation

 

>The profiles for the real cave I am working on were sketched along the
survey line.  That means they bend and twist as the survey line bends.  In
this case the survey line is very close to running down the center of the
cave, but that is not always the case. One leg from the T-Junction has a
"dog leg" bend in it.  At one station it goes from north to almost east for
about 70 feet, then it turns back to almost straight north.  The profile
sketches follow the centerline and so make the same twist.

 

 

      This means your sketches are 'extended', so if you want to use them
faithfully, without redrawing, you will need to use -projection extended.

 

 

>Since every profile sketch has two survey stations (or more), Therion can
morph the sketch to the data.  If a view angle is specified, does it mean
that some sections of the profile will be morphed more than others?

 

      Yes, exactly, however if the passage is traveling towards or away from
(or close to) the projection angle, the morphing will be very messy - hence
the desirability of sketches that more or less match the projection chosen.

 

So if all your elevations are -projection extended, then all selected
extended maps will be exported each time.  I should test it now, but am too
lazy, however my experience from several versions back is that Martins
suggestion of sequential selections and exports does not result in the
segregation of map outputs you are looking for.  Either Martin is right, or
will need to modify th-config between runs (or use indexes - not a good idea
in this circumstance - constrains your options later on for rearranging
maps). 

 

Have you though of using offset in your extended elevations as an
alternative to segregated output files? You know you can choose the starting
station and direction of branching in extended elevations?

You can use offset to separate passages that would otherwise overlie each
other.  This would give you segregated maps in a single file/run and the
relationship of the offset maps can be displayed by Therion in the form of
map-connection lines and preview above/below outlines. 

 

      Bruce

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