Digital Elevation Models + Aven

Olly Betts olly at
Wed Apr 20 12:26:37 BST 2005

On Wed, Apr 20, 2005 at 11:41:03AM +0100, Imperial College Caving Club wrote:
> 'Surface' legs are a good order of magnitude slower to render [due to
> the way the dotted-lineness of them is implemented?]

We just tell opengl to do dotted or dashed lines.  So it'll depend on
your graphics card and its drivers.  If solid lines are drawn in
hardware and dotted ones in software, then they will be a lot slower...

> and the colour depth-profile is rather useful to see where abouts our
> mythical 'walk in entrance at -700m' is going to appear, so I may look
> into creating a seperate 'flag' in the .3d files for 'DEM data'

Is there any benefit in converting the DEM data into .3d rather than
just allowing aven to read it directly?  Most DEM data will be in one
of a small number of formats, so aven just needs to know how to read

> and see whether it can be rendered as something pretty +
> semi-translucent with GL.

Mark wrote some code to render surface terrain already.  It's not been
folded into the current development version yet, but I'd suggest at
least looking at it, and probably reusing much of it.  He rendered the
terrain as translucent on top, but opaque when viewed from below,
which was pretty effective.


More information about the Survex mailing list