Saturday, August 17, 2013
Tiny Tiny Changes
It's really a bit crazy how much work it takes to get from one picture to the next in that series, especially since I would challenge most people to be able to tell the difference between any of them (except for the obvious background color change). From top to bottom:
First, the image from yesterday. This is an image used as a diffuse texture map, mixed with a pure white glossy effect to represent oil on the skin. That's it.
Second, I've added in sub-surface scattering (representing light that travels into and gets scattered from inside the skin). This is a single sub-surface scattering shader mixed with the diffuse color on the previous image and that result, in turn, mixed with the gloss. I think you might be able to see the effect if you look closely at her right nostril. Seriously, I'm not kidding. I doubt I'm going to go for a full-on three scatterer model for this exercise, because it's a whole lot of work for a minuscule effect. I'm fairly satisfied with what I got out of one shader, and I'll save fooling with the more complex and realistic treatment for some other time, maybe when I'm using stronger back lighting. (Honestly, I want to get on to the eyes and hair.)
Third, tweaking parameters on the gloss and sub-surface, adding a bump map to break up the gloss and make it look a little less plastic, though I'm not sure how well that worked, and also a mask to represent how skin tends to be more oily or sweaty on the forehead, nose and under the eyes compared to the cheeks.
Finally, adding a texture map (a reddened version of the diffuse texture) to control the sub-surface scatterer and restore a bit of the color variation (notice how the mole on her cheek is a bit clearer again in the last version compared to the middle two).
So, I think I'll call it a day with the skin shader and move on to the eyes for the next stage.