Not really "architectural glass"

[shelshok]

I got really excited seeing architectural glass as a new feature, but then realized that it's just the fake shadows setting that's been there for a bit in the betas.

This unfortunately, is not what the concept of architectural glass is in other rendering software.

The main point is that in architectural renderings, most of the glass comes in the form of windows, and in most cases, it's safe to assume that entrance and exit surfaces are parallel and very close, and therefore refraction and inner reflections are unnecessary. Of course, index of refraction still controls how reflective or transparent an architectural glass material is.

That makes it possible to have windows in buildings and cars as a single surface, which is easier to model, faster to render, and "cheaper" to store (think of each pane of glass as two triangles vs 12, and think of curtain walls modeled as single large surfaces vs all the panes that might have to make them up for correct refractions).

It would be nice if in addition to the fake shadows setting, specular materials also had a "no refractions" toggle.

PS: I am currently using a glossy surface with a falloff map for the opacity, but there's no easy way to color the glass, and for some reason the falloff map's index does seem to affect reflections and transparency the same way as IOR does.

PPS: Also, specular materials, even with IOR at 1 and fake shadows on, still block "light" in ambient occlusion mode. That is something architectural glass probably shouldn't do.

PPPS: I guess what I'm getting at is "architectural glass" is somewhere between the current glossy and specular materials, but neither does it quite right.

[FrankPooleFloating]

Architectural Glass is not my specialty, but it is the weekend and there are not a million dudes here... And I see you only have 8 posts.. so I am assuming you may be new(ish) to Octane...

PPPS: I guess what I'm getting at is "architectural glass" is somewhere between the current glossy and specular materials, but neither does it quite right.

You say between specular and glossy... have you tried Mix Material and plug both Spec and Glossy in and see if this can do it for you?

(you control Amount (mix) with falloff, I believe)

[shelshok]

Yes. The problem is that while that does make nice looking glass, specular materials are apparently opaque to ambient occlusion.

[FrankPooleFloating]

Outside of Abstrax (et al on Octane team), the one person that comes to mind that would
absolutely be able to help is GabrielFX.. I think he may do Architectural stuff exclusively..
and no doubt has complete mastery over arch glass.

http://render.otoy.com/forum/memberlist ... le&u=16083

maybe PM him?...

[FrankPooleFloating]

Fooze says this about Arch Glass in a LW Plug thread:

One of the reasons we sometimes call it architectural glass is because that's where we see it to be of most use. In most arch-vis for the windows you don't want them to cast shadows or produce proper caustics (which is slow), all you want is for the light to get through into the room quickly/easily.

Even with PT or PMC, without fake shadows, the only light getting through a specular material is the caustics which is very accurate, but very slow to render/calculate.

To control the reflection amount based on viewing angle use the index slider. (so the specular material naturally does this anyway). If you want even more control, you can use a falloff node for the reflection parameter.

[roeland]

If you want single sided polygons in your windows, assign a material like this:

Use a mix material with:
- Amount: falloff map, default settings
- material 1: Glossy material: specular 1.0, index 1.0 (i.e. a perfect mirror material)
- material 2: Specular material: index 1.0, fake shadows on, and pick a color for the transmission input.

--
Roeland