Glazing

[grasshopper]

Hi All,
I'm setting up my first scene using Vray advanced and have a couple of questions about the best way to set up my glazing.

1. I have a glazed wall with thick timber frames, Is it best to use 1 large plane of glass stretched across the entire wall or is more effective/efficient to have smaller individual planes.

2. Should I use planes with a double sided material or should I use boxes or should I use 2 planes with a single sided material.



As you can see the building has a few glass panels and this is just the foyer so the initial setup could kill or cure the final result.

I know this is some pretty basic stuff but I might as well set it up correct to start with. Also if anyone has any fabulous tips on materials especially glazing and timer please feel free to vent them.

I need to produce internals, externals stills and animations with a new renderer (VRay) of a highly complex grade A listed building so I’ll take all the help I can get and im sure there will be more questions to follow.

Cheers

[joconnell]

As a general rule and as a good work practise your glass should always have a thickness to it - if a raytracer is calculating refraction (in your case not much but thats besides the point) then it needs to bend light going into a glass surface and bend it again on the way out - If you only have a plane surface then the light will bend on the way in, but never bend on the way out and you'll get some strange refractions - It'll be as if the objects behind the glass are completely encased in it and the other side of the glass is way of in the distance.

The next thing is that if you ever have a glass panel where any edge is not encased in a frame and visible in the render, having thickness to it will give you a nice edge to get some glinty highlights in the reflections and also get some nice details with all of the internal refractions of the glass bouncing around.

As regards using a large plane running through the lot again I'd advise using a box so you don't get really weird refractions and a regular vray material. Set your diffuse to black, your refract to white, your reflect to white and turn on fresnel reflections (fresnel will make the reflections stronger at glancing angles and weaker when looking at the glass head on). The only thing you may find is that if you are looking at the glass in a way where you can see inside the frame, by using a box that runs through the entire wall you're not going to get the internal refractions and reflections that happens in glass but again that's a minor detail. As regards using one large box vs individual boxes per window pane they look the exact same aside from the detail above.

Reflections seem to be very much a personal choice and you may find that turning on fresnel with a white reflection colour doesnt give you the result you want. For something a little more tweakable, try putting a falloff map into the reflection slot instead - you'll get a falloff curve that you can use to tweak your reflection strength at different angles.

[grasshopper]

Cheers Jo, Nice answer.

For setting up the material would you recommend using a standard material with a Vray reflection or a Vray material with your recommended settings.

[ene.xis]

vray material all the way!
keep away from everything else!

[percydaman]

for straight arch glass, i just use plane with standard mat and vraymap for reflections. but ive gone both ways. imo its 6 of one, half a dozen of the other.

[grasshopper]

Is there no issues of render speed between using boxes or planes bearing in mind ones got a 2-sided material applied.

What about Vray mats Vs Standard mats which will render quicker with similar settings.

[Syclone1]

for most of my files that Ive tested, the vray materials render faster than the standard ones do... most of the time

-dave

[ene.xis]

and LC is not to keen on standard materials either....

[joconnell]

Is there no issues of render speed between using boxes or planes bearing in mind ones got a 2-sided material applied.

What about Vray mats Vs Standard mats which will render quicker with similar settings.

What percy above also mentioned is that if you use a standard material with the opactiy turned down, it's transparent without using refraction thus you don't get any of the weird volume issues associated with planes.

You do however need to put a vray map into the reflection slot to get vray to render reflections on the surface. As a general rule if you are refracting and reflecting, the vray mat will be quicker than the scanline as it's optimised for vray. For a case where you're only reflecting, the standard material + vray map may be quicker than the vray mat - Do a quick test scene and see what works for you.