Glass with 'blurry' light coming through


#1

I’ve been playing around with glass (Brazil + Neon) in an attempt to create a ‘mostly opaque’ roof for a semi trailer.

This material lets about 50% of the light through in a DIFFUSED manner and slightly tan colored.

I’ve played around with refraction glossieness, refraction glossiness, but those only effect what is seen THROUGH the glass, not the light coming out the other side.

Absortion changes the light traveling through, but does not ‘scatter’ it at all.

Dispersion also changes the light traveling through, but again does not ‘scatter’ it at all.

I’ve also tried applying a NOISE texture to several bump map places, but to no avail.

Conclusion: I only want to ‘scatter’ light after it goes through a slightly transparent object. The amount of ‘scatter’ (light deflected from it’s straight path) should be controllable.

Any ideas?

Yes, I can fake it by making the material emit light, but I’m looking for a long term solution. :slight_smile:


(Brian James) #2

Try adjusting the shadow for a directional light to be Brazil2Ray Shadows and then set the mode for these shadows to Rectangular with the dimension adjusted to taste based on your scene size. Here’s a sample… check out the directional light’s settings in Object Props.

GlassGlossyRefraction.3dm (144.9 KB)


#3

Cool trick! It also makes the shadows outside the test building blurry.

Thanks!

So there’s no way to tell a material (not a light) to ‘scatter’ light rays as they pass through?


#4

It’s not supported in Neon, but Brazil now supports “thin translucency” which sounds like what you want. Try making your roof a “paper” variant of the Brazil Advanced Material, or you can use the Thin Translucency texture in the…extra light? slot to add the effect to any BAM.


(Andrew le Bihan) #5

If I understand your question correctly, then you will probably need to use photons. You are talking about light coming through a piece of glass and landing on a diffuse object (like the floor). This happens by refractive transmission and is often approximated in raytracers by “transparent shadows” - otherwise known as “fake caustics”.

However, if you’re doing something out of the ordinary (like using a glossy piece of glass) then you’ll need to use real caustics - and this is implemented in Brazil using photon mapping.

Attached is an image and a working 3dm file that demonstrates this. The green piece of glass is non-glossy (ie - standard glass with a green filter). The red piece has glossy refraction. What you are seeing on the ground is the result of refractive scattering captured by photon mapping.

  • Andy

glossy_photons.3dm (111.9 KB)


#6

I think for the translucent fiberglass or plastic top of a semi as described here, the “paper” material would do the trick, no?


#7

I’ll give both a shot, thank you so much!!

This is what makes Rhino so great: The team at McNeel behind the product.

It looks like Neon does not support caustics, nor can I find the ‘paper’ anywhere in the ‘Brazil Advanced Material’. (nor ‘Thin Translucency’ in any of the texture slots)

Brazil 2.02 from 2012 is what I’m running. Looks like I can update to the 2013 version and see what other goodies await. :smile:

As for this particular project, I’ll be using the ‘Material as light’ option, or a couple linear lights to do the trick.


(Andrew le Bihan) #8

It depends what you’re looking at Jim. If you’re looking at the glass, then you will need the thin translucency shader to get the right effect on the “back” of the glass. If you’re looking at the floor then the problem is transmission - and for that you will need photons.


(Andrew le Bihan) #9

Yup - right now, Neon doesn’t support photon mapping.

Update your Brazil to SR3 - that will add the paper shader.