Translucency - Thickness or not

[fAEkE]

As far as I know you need thickness on your modell for translucency to work. I have been working with trees for a while and trying to get realistic results, and the best results have been achieved with fastSSS2. The problem is that I need thick leaves and not only a plane, and it doesn't work when using opacitymaps aswell since fastSSS2 don't have an opacity slot.. I have tried Vrayblend with fastSSS as base and the opacity as coat but it does not work since the borders are cut right of and you see the leaves inside which is black, causing a black border.

I read on forums and asked around, and finally I looked at evermotions archmodels vol 58 and the materials they use. And to my surprise they use VrayMat with translucency for their leaves which do not have any thickness.

Can someone explain this to me? 2sidedmaterial just does not cut it imo, but I still need the leaves to be single planes.

[simmsimaging]

evermotion is not usually the best place to go for materials IMO. Have you seen Peter Guthrie's site and tutorial on 2Sided material for leaves? I think it should be good enough for any case where you can get away with opacity mapped planes for the geometry. If not you are stuck with properly modeled leaves if you want to use SSS materials, AFAIK anyway.

b

[fAEkE]

Thanks for the tip, I'll take a look at his site. But the funny thing is that translucency works. I have been testing all day and for some reason both blurry refractions and translucency worked for the single plane leaves...

Can anyone explain?

[fAEkE]

Vlado, can you explain this?

I really need to know how this works. I'm going to use fastSSS even tho I got single plane geometry as it looks now because 2sided just doesn't work the way I want, but if SSS on geometry with no thickness is just a bug, then ofc I don't want to use that either.

[samuel_bubat]

If you need thick leafs than you´ll probabely have to go with real sss. anyway I would try to fake it somehow as your rendertimes will
skyrocket.
Regarding Evermotion. They make fantastic models, but their materials are sometimes totally over the top. Using reall sss on planes doesn´t make
sense at all (And that´s what they do in every plant model i´ve seen from them). You can get the same effect with a Vray2SidedMat or even
a standard material (without control in case of a standard mat.)

What exactely doesn´t work when using Vray2SidedMat ? It should give pretty much the same effect as when using real sss
on a plane without thickness, expect a lot less rendertime.

[fAEkE]

Yepp, seems like they use translucency for all of they plant materials. My first reaction was "wtf", but when I tried the material with and without translucency, and a 2sidedmaterial, the evermotion one gave the best results. I dunno, 2sided just don't work well for me.. It is fake SSS so I guess I should not expect it to work as well as that, but imo it's much worse. Maybe I don't understand 2sided enough to get good result, even tho I have read about it three times in the ultimate guide..

I looked at Peter Guthrie's material and yes, it looks good in that render when it is a closeup with dof, but how will it work in a huge scene where you have a clear direction of light that need to be emphasized by SSS effects on the trees? In my experience with 2sided you just get an SSS effect all over the place.. thats the problem I get.

Well, I have seen good results with 2sided so ofc it works. I just have to learn.

Anyway. The part I want to know is why the result changed at all when using translucency on single planes (the vermotion material). That must be a bug?

[Deflaminis]

I've been a fan of using the 2 sided for trees far away from the camera with some real leaf models in the foreground if necessary. A scene full of modeled leaves with SSS must really hit hard in render times, though with instancing perhaps not as bad as I would expect.