[Radiance-general] oconv and rtrace_dc warnings for non-planar vertices

[Thomas Bleicher]

On 11 Jun 2008, at 21:24, Ramana Koti wrote:

> oconv: warning - non-planar verterx for polygon "f_1719_0" (this  
> happens for 20 or so polygons)
> rtrace_dc: warning - non-planar vertex for polygon "F_1636 (Can't  
> see the rest of it, this happens for probably the same polygons but  
> not in the same order)
>
> I used the SketchUp to Radiance su2rad plugin to export geometry  
> from a sketchup model and I had to start the simulation before  
> DAYSIM refreshed geometry display since it was taking too long to  
> do that.
>
> How serious are these warnings and why are they occuring?

The export of polygons from Sketchup has only a limited accuracy.  
This results in some
cases in polygons where one of the points is outside of the plane  
defined by the rest
of the vertices. Radiance has a built in tolerance for these points  
but when that's exceeded
the warning is generated and the vertex or the whole polygon ignored  
in the rendering.
I'm not sure about the last part but maybe someone else knows better.

Relevance: If the polygon is ignored and it is essential for the  
geometry (ie a wall of a room)
then it is relevant. If it's just a tiny piece that doesn't do much  
for the lighting it's harmless.

To avoid this problem export with the option 'triangulate'. This  
creates polygons with
only 3 vertices. Much more polygons in the scene but no warnings.

Regards,
Thomas