Frosted acrylic

[Shopper2]

Hi guys,

Im having some trouble creating a frosted transparent material.

I want to create like a matt frosted (smooth) white transparent plastic. It either starts to look like a rough sandpaper (with glitter) if i turn down the reflection and refraction glossiness and tends too look like a bump map. Also the more i fine the noise the crazier the render times go. Even a small corner of this sheet (see pic) takes like 10 min with low settings and i have to go to like 2000 x 2000 px and cant afford to wait 10 hrs.

Am i doing something wrong....is there other ways to create this look. I have tried the translucent way but i cant get it transparent enough.

I guess what im doing gives me the right result, its just looks to rough and it just takes waaaayy to long.

Any ideas?

Thanx

Justin


http://img164.imageshack.us/my.php?image=frosthr1.jpg

[dalomar_cg]

Re: Frosted acrylic

Well the frosted sand paper look is basically noise from the sampling on the glossy reflections/refractions. To increase the quality and make the results smoother your going to want to increase the subdivisions. Doing this will increase render time, so add as many as you can.

As far as speeding up the calculation I'll through 2 things out there. First off is that LC has the option to use some of the rays traced during those calculations for the glossy calculations. This shows a definite speed improvement, it doesn't make it lighting fast but it will help. When doing that keep in mind that the quality/speed of calculating the glossies is tied to the LC solution, so a bit more refinement on that end will help. The second thing pay a little mind to your Image Sampling settings. If your using Adaptive QMC (which is enabled by default) that will add a bit of noise and make it harder to get those smoother results. Adaptive QMC is also a takes a bit longer to calculate than Adaptive subdivision.

Oh and lastly, if your really looking to save time you may try ditching the Reflection glossiness. There are some types of glass which are frosted from one side and still shiny from the other, so doing a material like that may free up some time. Hope this helps.