Transmission workflow

[gardeler]

I'm trying to achieve a strong translucence effect and having quite a lot of difficulties achieving it. My logic says this:

Create a diffuse material. Make transmission color the amount of transmission you would like;
like 80% white would let 80% of the light continue through the surface into the next and so on. (I would like to have it only block 5% of the light for my test.)

But no, that is not how it currently works. You have to crank transmission up to lets say 100% white and then make your diffuse color darker than 100% white. cause white means that no light can continue through?? If you make it black, you get the max amount of light to continue. Not very logic, but I can live with that if it did what I need.

But despite many tries I cannot get enough light to come through. The first surface it goes through gets very bright, but when hitting the next, it has lost a lot of light and does not let me get the look I try to achieve.

I can try to do this with a specular material, but that looks more like a frosty plastic bag and not like a backlit bed sheet, or a shirt.

When OSL finally arrives it should be simple for those of you that can code to do a shader that can do this, but is there anything I can do with the current tool set to achieve this?

[BorisGoreta]

Well if the material is 100% diffuse that means that it reflects the light 100% back in a diffused manner, meaning in all directions but only on the side where the light hits meaning no light can pass through the material ( transmission ) since all light got diffused. If you lower the diffuse level to 80% then 20% percent of light can pass through as transmission if you have transmission set to 100%.

[gardeler]

Thanks for the reply, that kind of makes sense. But I still cannot let enough light though. (like hanging two shirts in front of each other with a strong back light.) Vray does this quite easily by using the 2 sided material.

[BorisGoreta]

Are you using path tracing ? I think transmission does not work properly in direct kernel.

[gardeler]

Are you using path tracing ? I think transmission does not work properly in direct kernel.

always!

[ciboulot]

Did you try to put a scatering in the medium slot?
With a very small scale and a little scatering strength, no absorbtion.

It might work this way.

[rashadcarter]

You can also raise the Transmission Value beyond 1. For some darker skinned characters I've used settings as high as 8. But this also means you've accounted for depth in the Medium settings.