[Yafray-devel] Re: Fresnel effect too dominant for IOR=1.5

[GSR - FR]

Hi,
address@hidden (2008-01-14 at 1235.46 +0100):
> On 13/01/08 20:26:41, GSR - FR wrote:
> > Hi,
> > address@hidden (2008-01-13 at 1055.51 +0100):
> > > IOR. Comparing it with the blender internal raytracer and physical
> > > values (5 and 1.25,
> > [...]
> > > By the way: When disableing RayMirror in the Blender yafray settings
> > > the fresnel effect does not disappear. It just seems to influence
> > > the shading ad the sides of the glas.  I'm using yafray 0.9 and
> > > blender 2.45.
> >
> > Blender internal as ref is not a good idea, bugs,
> > inconsistencies... more artistict than real.
> >
> https://projects.blender.org/tracker/index.php?func=detail&aid=7910&group_id=9&atid=125
> 
> Thanks GSR for Your reply.

It was just a private note (quickest demo I could find of "blender no
good ref"), but this one is public.

> I know about that bug but I don't think it does concern the fresnel effect.

The point I was trying to comunicate is that the internal render
engine is not physically correct in general (bugs + on purpose on some
parts) so you better focus the issue from other point of view, you
will stop getting headaches wondering what is going on. ;] There are
more demos of just doubtful correctness, like arealights vs point
(smallest arealight should render something that approaches plain
point light, but it does not, does it?) or artistic optimizations
(hair shading trick that mixes surface shading with strand one).

No idea if yafray is physically correct or tries to, nor if params map
perfectly, but your best bet is looking at its code (comments? docs?)
and use allowed params until it looks OK to you or looks the same than
a photo or than "this is physical correct" renderer's result.

GSR