Frosted Glass Challenge (Any Render Engine)

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  07 July 2010
Frosted Glass Challenge (Any Render Engine)

Over on the Maxwell forum, there has been a challenge issued to all other render engines, biased and unbiased, to create a realistic frosted glass material and render it on the supplied scene. Please have a read below, and if you care to, submit an example from your render engine of choice so we can fill the empty slots:

Tom wrote: A few days ago, I've revisited H.Jensen's frosted glass dragon scene with Maxwell Render V2 and
it turned out pretty satisfying in terms of quality I've expected. As you see, the scene is very simple
and it's only demonstrating rough dielectrics. The subject is not very challenging for most of the biased engines
but, it could be a real pain when it comes to unbiased cores unless they are not properly optimized/implemented,
especially for interactive and realtime rendering as their BSDF and microsurface approach is playing a huge role.

Here's the original work done by Henrik Wann Jensen (2003):

Below is the frosted glass dragon rendered with Maxwell Render V2:

So, I thought I should share the scene and you may give it a try with any other engine you have access.
Of course, this is a quality/ability test rather than being a speed-challenge.

The scene has a blue studio ground, a dragon, a small emitter plane and a dim skydome as ambient to match the original reference.
But, you can use either of them or both or more when the features of the engine don't match (only emitter, only skydome or only IBL or all).

Here's the scene OBJ files (all pivots at zero, no further relocation needed):

Resolution: 800 x 640
Lens: 85 mm

You may also try FBX file instead:

There are 3 goals in doing this:
1) Highly rough transmissive surface achieving blurry refractions.
2) Full caustics and TIR including the caustics on its own shadow.
3) Clear glass material core with no SSS/translucency or other effects is essential.

I want to leave this test open to any kind of render engine for comparing the quality of outcomes to Maxwell Render.
This is not a duel, so my respect goes to the ones which can at least succeed and demonstrate its quality in comparison.
And of course it's very sad for the ones which may fail awfully. Let's see... Awaiting for your renders...

Dragon model by Stanford University Computer Graphics Laboratory.
Reference image rendering by Henrik Wann Jensen.

-Edit: Building the table of entries... Below is the current state:

Full Size:
Brian Looney

Last edited by Bubbaloo : 07 July 2010 at 12:25 AM.
  07 July 2010
Just a few questions who might come handy for those participating...

What is the exact rgb tint of the blue ground?
What ior is used for the glass?
What color and power does the ambient light have?
What color and power does the emitter plane have?

Any chance of sharing the maxwell scene?

Last edited by ACiD80 : 07 July 2010 at 06:08 AM.
  07 July 2010

Here is the Maxwell file:


Glass IOR = 1.51

Ambient Light:
Sky Dome
Color 255
10000 cd/m^2

Emitter Plane:
Power=300 watts
Efficacy=125 lm/w
Output=37500 lm

Camera Settings:
Focal Length=85mm
EV Number=12.492

These are the initial settings. MultiLight may have been used to fine tune the final output. The scene was set up as simply as possible so as to easily compare results of rough glass between the various render engines. It should be sufficient to start with these initial settings and make minor adjustments to lighting levels to approximate overall scene lighting.

Good luck! Hope to see all engines' results!!
Brian Looney
  07 July 2010
Yeah, vray looks more realistic. Thank you, now I will use vray.
  07 July 2010
Originally Posted by mister3d: Yeah, vray looks more realistic. Thank you, now I will use vray.

I'm pleased that you found this render engine comparison helpful in your decision making process, although so far only 3 engines have been represented.
Brian Looney
  07 July 2010
Interesting challenge, I was looking forward to this thread .
Too bad the entries seem to stall.
Anyone care to step in ? (Luxrender anyone?)
  07 July 2010
Originally Posted by mister3d: Yeah, vray looks more realistic. Thank you, now I will use vray.

My sarcasm detector is detecting something here.
Free rays for the masses
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