Secrets of Swimsuit Babeby Jimmy Chow, Hong Kong
Lips
The lips require special treatment as they’re very different from the skin due to their
reflective nature. The anisotropic shader is good at producing this kind of reflection.
It is connected to the first layer in a mix8layer whose base layer is just black. A
mask for the lips is required to apply to the opacity channel of the first layer so as to
exclude surfaces outside the lips, as shown below:
For the swimsuit, the third party shader p_MegaTK (see appendix section for URL) is used. It is an extremely slow shader when it involves indirect illumination and refraction. Most of the render time was actually consumed by this shader.
The fog is a 3D containter of fluid effect. The floor is a reflective car paint phenomenon. The background is an anisotrophic shader with some noise in the incandescence channel and is in a separate scene file with different lighting.
Compositing
There’re basically two elements: the character and the set. The former requires a
beauty pass, specular, reflection, hair, eyelashes and lips reflection. The latter
requires background, floor and fog. Separate alpha passes for the character, eyes and
swimsuit are also required. The node network is shown below.
How the character is comp’ed is trivial except for the eyes and legs where the fog is in front. The eyes’ alpha does not work as a mask. It is to multiply the beauty pass. In this case, a light outline would appear below the eyes. It looks like the reflection along the lower eyelid. This fake works well because the image resolution (1500 x 1000) is not too high to reveal details.
The fog needs special treatment because part of it is in front of the feet and there’s some DOF (depth of field) effect. It requires two fog passes: one includes the character and the other does not. The former pass is used to obtain the fog in front of the feet and it would be put over the character. The DOF effect is faked with a ramp and an IBlur node on the latter pass which is then put under the former.
Command Line Rendering
The batch file used in command line rendering is shown in the following figure:
There’re two scene files, character (babe.mb) and hair (babe-shave.mb), to render and they share the same command line (under :RENDER) with different options as variables. Different passes are put into different render layers which are indicated in the %layers% variable. There’re also mel scripts (eg. renderHighQuality.mel) which update the sampling attributes (eg. render settings, area lights) to control the quality of the output image. The scene file for the background is not included in this batch file. The total render time of all layers is about 3 hours with sample level min=0, max=2. It takes 5 hours to render if sample level min=1, max=3 without noticeable
improvement in image quality.
Epilog
I think I’ve achieved my objective within the limitation I’ve got: amount of physical memory, number of computers, level of skill. If I’ve got more memory, I can do more in ZBrush. I have only got 1.5 million polygons with the 1.5GB of RAM I’ve got. This is not enough for this full body character. That’s why I gave up displacement map in the end as I didn’t want to separate it into several pieces. If I’ve got a couple of computers, I can break up the image into several pieces and render them simultaneously so that I can do more tests especially when displacement
map is applied and when the shader is too slow like p_MegaTK. Finally, I think I’ll make another image of her and I’ll give her a name next time.
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