Subsurface scattering density colour

Started by Hannes, October 21, 2019, 03:13:33 am

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Hannes

In our SSS tests we found, that if you plug in an image map to the "volume 1 colour function" slot, the density is completely black unless you check "repeat x" and "repeat y", but then the UV mapping doesn't match. So KyL had the idea to plug the image map shader into the "volume 1 density function" slot. The UV mapping seems OK, but after numerous tests, I found, that it only reads the black and white information of the image map, but no colour information at all. I tested it by setting the decay to 0 to see, if there is any colour. The volume 1 color was set to grey, and for testing I applied an image map shader with an exaggerated green tinted texture map of my object to the volume density function slot, but the rendered head remained grey. Of course it seems logical, that for density TG only reads b/w information, but so I assume, it's not possible at the moment to apply a correctly placed colour texture to a glass shader, that's set to subsurface scattering?

Matt

I realized what causes this. In build 4.4.39 the colour function is evaluated volumetrically, which makes it quite powerful but it forces it to lose the UVs. This week I'll add an option to choose between surface texture coords and volumetric world space.

The density function is evaluated at the surface so it is able to use the UVs. The greyscale behaviour is a current limitation, but I intend to support RGB density functions in future.
Just because milk is white doesn't mean that clouds are made of milk.

Hannes


Dune

Ah, another riddle solved. Thanks Matt.

Hannes

OK, here we go!! Latest version (4.4.40) makes it perfect. And additionally: using an image map for the density colour instead for the density function is even a lot faster! This image here renderd in only half of the time. Cool!!
I have to say, that I'm really impressed by the quality of the TG subsurface scattering. I have seen renders made by other apps using SSS, that looked a lot worse and more unnatural.

Dune


Hannes


Dune


Hannes


Matt

Just because milk is white doesn't mean that clouds are made of milk.

Dune