IOR for glass in architectural images/animations

[tricky]

Does anyone, as a matter of course, set the value for Index of Refraction to 1 for 'architectural glass' in renderings, be they for still images or animation?

I assume this would have a big performance speed-up - am I right?

[vlado]

I can't really see why it would speed things up; there is still the same number of rays to trace, even though they may be in a slightly different direction.

Best regards,
Vlado

[tricky]

I see. I thought that becuase it wasn't having to calculate bending of rays for any given thickness of glass, it would be quicker. I stand corrected.

[tom schuelke]

for us it makes sense most time to use a usual fresnel value between 1.5 and 2.4, depending on the amount of relection that is wished in the final image..

while 1.5 seems to be more physical, reflections live frome the movement in real live. you can see very little reflections still, if you move, but you cant in a still image, when you dont move.

So sometimes its good to overexpress them, in still images, to make them-"visible".

thats why i often use fresnels aout two or more..


Tom

[tricky]

i'm really just talking about refraction.

[vlado]

Well, the calculations involved in computing the refraction direction are a really very very small part of the whole thing, so that's why it does not matter so much.

Best regards,
Vlado

[tricky]

I see - thanks vlado

[khoross]

if i understand correctly , what tricky wanted to know if there any way of making transperancy in vray without the raytrace calculation of refraction . as for standart max materials where u set the opacity value with no need of raytraced refraction, to speed up rendering.