Not really "architectural glass"
Posted: Fri Jun 28, 2013 5:51 pm
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.
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.