[Radiance-dev] Non-planar vertices

[Greg Ward]

Hi Chris,

The standard vertex epsilon in Radiance is set by the VERTEPS macro in 
src/common/face.c, and is 0.00001.  In other words, any vertex that 
exceeds this difference from the average computed plane of the polygon 
will result in a "non-planar polygon" warning.  Since your export only 
supports 4 decimal places, this will be triggered all the time.  The 
only way to avoid this error is either to switch warnings off (as I 
often do with this problem), or change VERTEPS and recompile.  Or, you 
can just ignore them.  Warnings are mostly there in Radiance to let you 
know something is not quite right, so if you spot a problem later (like 
cracks along object edges in this case), you'll have some clue as to 
its origin.

-Greg

> From: Christopher Kings-Lynne <chriskl at familyhealth.com.au>
> Date: January 23, 2005 5:26:19 AM PST
>
> We get lots of these:
>
> rtrace: warning - non-planar vertex for polygon "lyr_15_pol_158568312"
>
> When using Radiance on models that we have generated using our 
> Lightwave exporter.
>
> These polys should all be "flat", but the exporter only has 
> information down to 4 decimal points.
>
> How flat does Radiance require polys to be before giving a warning?
>
> Chris