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White translucent Matt Acrylic Plastic without SSS - HOW ?

Posted: Tue Feb 13, 2007 4:13 pm
by Q2
Hi everyone. I am struck with this kind of material. Can't get it to work.

I need to create a "semi transmittive and transucent matt white acrylic" material.

The problem is that I have 3 flat plastic sheets stacked above each other whith some space inbetween an a lightsource above the top sheet. This light source needs to lighten up all three sheets and these sheets need to let the light pass through and also be semi transparent looking AND need to have a pure white shimmer.

I tried to resolve it with a sss material, but that give a ton of noise an take forever to finish.

Any ideas on how to solve this problem?

Thanks a lot!

Q!

Posted: Tue Feb 13, 2007 4:42 pm
by NicoR44
you mean like this:
Image
or more like this mat?:
Image
or non of the above :)

Posted: Tue Feb 13, 2007 5:13 pm
by Q2
Hi Nico

Both look great but I am looking for something like in the second picture, except a bit whiter. But otherwise that's just it!!!!! How did you do it?


Q!

Posted: Tue Feb 13, 2007 5:17 pm
by tom
I just uploaded a milky one ;) Maybe that works...
http://mxmgallery.maxwellrender.com/new ... hp?id=1266#

Posted: Tue Feb 13, 2007 5:21 pm
by Q2
Thanks Tom. DOWNLOADING RIGHT NOW. Will tell you if it worked!

Q!

Posted: Tue Feb 13, 2007 5:49 pm
by Q2
WOHW, What happened?

After loading your material all materials in my material list dissapeared. But they still seem to be loaded cause I can klick somewhere in the all gray listfield and it opens the dialog field, but I can not see the list anymore. All grey on that side. ????

:?:

Even after reloading and rebooting nothing.... Maybe the my mac? Any ideas?

Will try on the other macs........

Q!

Posted: Tue Feb 13, 2007 5:55 pm
by Q2
Ok. Found something. I closed the Material List and reloaded it by dividing the Objects list. After that all materials reappeared!

Strange though!

:lol:

Now back to the material. How high would I put the absorbtion value to get the above shine through? 0,5 or 100 or even more? Does it depend on the object size? And how come I can't see it in my material preview window?

Q!

Posted: Tue Feb 13, 2007 5:56 pm
by tom
Now this is like "The Milk" series :lol:
Unbelievable... I don't think this problem has something to do with the milk.mxm
Can someone else please check it? (....or dare to? :D)
carstenquilitz wrote:How high would I put the absorbtion value to get the above shine through? 0,5 or 100 or even more? Does it depend on the object size? And how come I can't see it in my material preview window?
Materials don't need to be updated depending on object size etc. You know, a thin drop of spilt milk will let a normal light pass through but a meter cube of same milk won't, unless the light is not more powerful. However, you can surely change the material for your needs but this doesn't mean it remains as a milk :) If you want it to scatter more light, you should decrease absorption or increase the transmittance color. ;)

Posted: Tue Feb 13, 2007 6:22 pm
by Q2
Ah, all right. Will do some tests now. Thanks again for your help!

Will keep you updated!

Q!

Posted: Wed Feb 14, 2007 2:00 pm
by Q2
DARN. :(

Doesn't work out. Tom, your milk material does just not do the trick. It is not getting transparent enough and I have a LOT of noise, even after 24 hour of rendering time and a SL of 17.39. Isn't there any other way to make a material that has the mentioned characteristics?

Thanks anyway.

Q!

Posted: Wed Feb 14, 2007 2:12 pm
by tom
Transparent? No, my material is not transparent. It's just scattering the light inside. Please post a screenshot of your scene, an example or similar and let us know more about it. Maybe we can make something suitable for your need. ;)

Posted: Wed Feb 14, 2007 2:50 pm
by Fernando Tella
I think you should make it scatter only on the surface => roughness. Make it rough and give it some transparency with the transmittance with the color you want.

Posted: Wed Feb 14, 2007 4:09 pm
by Q2
Ok. Here are some pics. Sorry I can't show you guys more of the thing but my customer doesn't want this to be seen in public just yet.

Here's my problem:
This is a picture of the material I want to create:
Image

And this is the material I was able to create so far (includes SSS):
Image

Note that the whole scene is lit by one emitter which is located on top of all these plastic sheets and that I therefor need the material to be transmittive AND white at the same time. This rendering took 24 hours to bake and still has a lot of noise ( this is a 100% crop of the whole image), especially if you look at the matte chrome rim and the back surface which has a fine scratch matte finish which is overcasted by the noise here and therfor looks as if it is heavily sandblasted.

So is there a way to achieve this without SSS or the darn noise?

Any help is appreciated!!!!!

Thanks guys....

Q!

Posted: Wed Feb 14, 2007 7:14 pm
by michaelplogue
Try with a standard material with no SSS, adjust transmittance to what you want, and play with the roughness and Nd to get a similar effect. SSS adds a lot to the computations and results in considerably more noise. Using just roughness on a transparent/semi transparent material will achieve a similar result (though not exactly the same, or course).

Posted: Wed Feb 14, 2007 7:55 pm
by Q2
Hi Michael

I tried that already but as soon as I get the transmittance right and the material looks rough ok the material in the render turns out greyish and not (glowing) white like I need it. And after I add a second bsdf layer with a white color (214,214,214) weight 30, nd 5 and transmittance white it doesn't allow any light to pass through my material anymore. So it turns out that all sheets below the top one, are too dark. Maybe I do something wrong here.....

But never giving up here! Will keep you posted.

Thanks anyway.

Q!