Litracon material

[theory]

hey there, I've been trying to reproduce a litracon (light transmitting concrete) material with no luck what so ever,
I know that there is a couple of examples on the resources website, only they're so dated that they render very differently within V2

so, did any of you guys ever try to make this material?

litracon.jpg

[_ _]

glossy refraction with a map and something similar/matching in the diffuse?

[Matthew Spencer]

A quick-rendering method for this would be to make a conventional concrete material and then use an alpha map of the translucent pattern to clip the layer, with the pattern painted in a 50% gray or so.

By the way...I never noticed that Yemen and Egypt have extremely similar flags...

[theory]

hey there, you guys all make a valid point, only the problem is not the surface texture appearance, it's actually the light part that I'm having trouble with, i even tried to mask out or clip the fiber parts, but still i cant seem to get the right light permeability or translucency as opposed to transparency, and the 50% bit is used in the outdated materials that I've referred to earlier, and SSS wise that would be a performance killer, so i don't know, p.s. thin sss works like a charm only there's nothin thin about a concrete wall,

and yea they do look similar color wise, except for the eagle, when i saw it i was like, oh a fellow maxwell user from egypt, then i saw that's yemen, and i was like close enough

[_ _]

its all about cheating and experimenting - i wouldn't try and make a 'physically correct' version
is it for a still or animation?

where are your test renders?

[theory]

this is not about physical correctness, this is why i ruled out SSS, and i'm using it for a still,
here's a test, there're 4 boxes behind this wall 2 of which are pressed up right to the back of the wall,

lit.jpg

this is the closest I've gotten, you can see it's a transparent as opposed to a translucent effect, i had to grey out the top layer's mask, and the result are pretty crappy,

[_ _]

what about glossy refraction and a closer up view?
what kind of maps are you using?

[theory]

here, along with the scene and the used material,
the used material is simply put together to test the light permiability, so i overlooked the material surface qualities (glossiness wise) for now,


closeup.jpg
https://rapidshare.com/files/2722403055/litracon.rar

[Matthew Spencer]

Are you applying your test material to a plane or a volume? If it's a volume, then you're seeing two parallel faces with the texture mapped to both of them, which means you're getting the visual effect of 2x the transparency.

Anyway I whipped up this test scene


The material is two layers: one rough translucent layer which sets the appearance of the "streaks", and one clipped opaque layer with a bump map for the concrete texture. So basically the clipped areas of the concrete layer reveal just the rough translucent layer.

So to tune the translucency of your material, it's going to require the delicate tweaking of a few fields; there's no way to avoid this. Play with the opacity/weight of each layer, play with the transmittance of the layers, and play with the contrast/brightness of the clip map.

[theory]

well i need the wall to be at least 25 cm thick, that's a must, so it's a volume, see the link to the scene at the end of my last post, maybe i could throw in a subtle emitter layer to make up for the translucency comprimised on account of the thickness, idk!!