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View Full Version : [SSS] Backscatter not working with some objects

m4gnus
10-01-2009, 09:58 AM
Heyho!
I'm creating a scene with a rose in it and i want the rose petals to have subsurfacescattering(misss_fast_simple) on them.
It worked fine on the ones i created in maya but as soon as i exported them to zbrush, sculpted them and reimported them to maya the backscatter doesn't work.
The petals have some volume(i extruded all faces by a small amount along their normals, so that they have some thickness) and are about the same scale as the unsculpted ones.
I really tried everything i can imagine but i just can't get the SSS to work on this. Even changing the Backscatter weight to about 100(all other wights were below 1) didn't change anything.
The normals are also fine, i have no idea what the problem could be...
I attached a render with the unsculpted petals(on the left), 4 sculpted petals(on the right) and a sphere in the middle. Every object has the same shader(miss_fast_simple) applied but still the sculpted petals look very different than the other objects.

You can find the scene file here (http://mitglied.lycos.de/m4gnus)([Right click on Backscatter Prob Scenefile->Save Target As] binary,created with Maya 2010 x64, but i might be able to convert it to an older version).
If someone could check if i did something horribly wrong or if the error only occurs on my computer i would be very grateful.

Thanks in advance,
m4gnus
Eshta
10-01-2009, 05:51 PM
check the object normals , the facing inword
they should face out
m4gnus
10-01-2009, 07:36 PM
oh god....yes that was the problem...i thought the normals looked ok, but reversing them solved the problem.

Thank you very much!

Edit:Man, those SSS shaders are just buggy on my computer... it worked fine for the simple test scene but now i tried to export a denser mesh from zbrush and now there is still no sss even after reversing the normals(i also tried reversing them again)...
I guess i'll have to find a workaround or paint the rest in photoshop :(
or is somebody interested in solving a puzzle? if i have some time i'll create another test scene at the weekend and somebody could try to get the SSS working. i might hand out a cookie if somone manages to solve it ;)

regards,
m4gnus
Libor
10-02-2009, 02:48 PM
...watch out also for scale of the object maybe the scattering is there but not visible

...there is "Scale Conversion" factor in SSS shader attributes so try to change it radically i.e. from 1 to 100

should help

P.S. dont forget to connect lightmap node to the shading group of your object! (when you assign new sss shader to your object it happens automatically but not when you connecting old sss from different object in your scene!)
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