Export elevation over steepest path

[Olly Betts]

Martin Sluka wrote:
> detrito wrote:
> > I would like to export my cave project to SVG, producing the classical
> > plan and elevation maps.
> > 
> > I used the aven "File > Export as > SVG" export-tool: the plan view is
> > graat, but I was surprised by the elevation export. the
> > elevation exported map is actually a view of the cave from one side.

It's a projected elevation.  If you want an extended elevation, you
first need to extend the survey, and then export that as SVG (or
whatever format your want).

> > I would better produce an elevation export along the steepest path of the
> > galleries (the classical way to represent the vertical development of a
> > cave).
> > 
> > is this possible and I did missed something? I never looked at survex
> > code: if this option is not already present, could you suggest me which
> > files should I look at in order to implement it?

See the "extend" program, which as of 1.2.27 you can now run in
automatic mode from aven (menu entry File->Extended Elevation).

However, it doesn't provide exactly what you describe - in automatic
mode it will prefer to follow legs along a survey, and in cases where
there are multiple legs to choose from (i.e. a junction within a survey,
or a junction where none of the unvisited legs are in the same survey
as the leg we arrive on) it'll pick one arbitrarily.

Following the leg with the most downward angle when there's a choice,
that shouldn't be hard to implement (though it seems prone to
misbehaving - the true "deep route" might not be reached via the leg
which exits the junction at the steepest angle).

> In Therion you may use command  "extend" (left, right, none, ignore,
> ...) in centerline section. 

Survex has very similar functionality for controlling the extending (and
has since before therion did I think, so I assume therion's support is
inspired by Survex's).

However, I don't think therion supports following the deepest route
automatically either, and doing this by hand would be rather tedious.

Cheers,
    Olly