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

[lynx . abraxas]

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.

I know about that bug but I don't think it does concern the fresnel effect. In
my test setup with the wine glas and the glas cubes the cubes look  all  right
but the outside of the glas bowl reflects the surrounding too much although it
is empty.
It looks like glas that was sputtered with a mettal from the  outside  (I  did
that in my physics theses). It's too close to a normal mirror. The front scene
with the cubes is fully visible in the glas which shouldn't be  for  a  normal
unsputtered glas.
Using  the  blender internal raytracer this effect  can be nicly controlled by
the two fresnel parameters and those adviced realistic parameters (5 and 1.25)
yield  a  very realistic result. But a far smaller fresnell value is necessary
to achiev the same effect with blender internal as yafray gives with a fresnel
offset of 5.
My  problem is that I can't find a way to reduce the fresnel effect further in
yafray. Negativ values for the fesnel offset in the  xml  file  didn't  change
anything  so  I  assumed  there  might  be  a  wrong  scaling parameter in the
calculation of the fresnel effect in yafray code. (there is  a  comment  about
1/2 in the yafray fresnel code)
I have put my blender file at 
http://www-nw.uni-regensburg.de/~.grr06742.back.physik.uni-regensburg.de/BLENDER/CAUSTI~1.BLE.
 I also tried yafray from svn yesterday but no improvement.
I'd  be  very  happy to get the scene rendered in a realistic way and I'd need
yafray for it because of the great caustics it can do.

Thanks for any hints or advice
Lynx