Indentations Sucka :or: Lighting in the 3rd Dimension
by akrid
Today on [Title Forthcoming] I resculpted my retopologized mesh at a leisurely pace throughout the week, resulting in this: The face needs another go... 2 hrs of work down the drain... I thought talking about the displacement maps in this image may be a good topic. But I'm finding it spans a few too many areas that I have yet to mention to be an effective thing to cover. I've decided that I wan...
Today on [Title Forthcoming]
I resculpted my retopologized mesh at a leisurely pace throughout the week, resulting in this:
The face needs another go... 2 hrs of work down the drain... I thought talking about the displacement maps in this image may be a good topic. But I'm finding it spans a few too many areas that I have yet to mention to be an effective thing to cover. I've decided that I want this understandable without any previous knowledge, and I don't want any gaps or misunderstandings by the end of it. Suffice to say I'm sure this topic will come up later as I work, so I'll leave this to a later date.
So instead, lemme tell you a lil sumthin bout lighting, a subject that is simple at it's core but has an incredible amount of depth.
GI (Global Illumination)
it broke :( ------------------------------------------------------------------------------------------------------------------------------------------------------>
Left is real, right is CG The main concept I worked around in lighting this is a technique called "Global Illumination". In traditional lighting of yester-year, lights in the scene cast rays. if the rays hit geometry, they light the surrounding area. Global Illumination, or GI, takes those rays and gives them the ability to bounce. This allows the ray to cast off and light another object, with reduced intensity according to the distance traveled, also taking in to account the color, reflective, and refractive properties of the geometry. GI also allows for new effects, such as colour bleeding and caustic refractions. Over pretty recent years, GI has brought us leaps and bounds closer in the goal of imitating the real world. Infamous tests like the "Cornell Box" and it's permutations have put GI through it's paces, comparing pixel for pixel the differences between a real image and a synthetic one. The GI method has proven to be startlingly accurate.
GI: 1m 25s Non: 51s But this accuracy does not come without a cost. Render times skyrocket with most types of GI, making it generally impractical for CG movies, and certainly impractical for games (although some make claims, I remain confused Crysis 2). So far GI has been mostly restricted to still images. Even if it does become viable as hardware improves, GI severely limits the users control over the lighting. It also obviously lends itself best to a realistic style, something a lot of artists don't want.
(Also note that GI is a bit misunderstood. It usually refers specifically to that outlined above in practice, but conceptually [I.E., to programmers] it refers to an entire group of modern algorithms and techniques that are used to light scenes. That outlined above is properly referred to as indirect illumination. I know, it's stupid and confusing, but there seem to often be disagreements between the technical side and the artsy side. Suffice to say, when you turn on GI in a 3d program, you're usually turning on some form of indirect illumination.)
Light Setup
Anyway... Specifically what I did with the scene:
- Three directional lights at the front, back, and far side of the model. These lights light the entire scene evenly from a specific angle.
- Two point lights by the eyes, that are set up to light only the eyes and not the skin. These lights illuminate evenly in all directions.
- Two strips of white polygons, that are only visible to any reflections in the scene (I.E., the eye). This gives it a nice little glint.
- GI allows me to use much fewer lights then I would need otherwise.
This is by no means the best light setup. Hell, it isn't even a good one, and I'll adjust appropriately as I work on this model more. But I think it serves it's purpose as a demonstration of what's involved in lighting a scene. That's basically all there is to it, but it's a simple to learn hard to master kind of deal, and you can see how someone can go crazy with things like those reflection polygons. I'm also sparing you the nitty gritty technical specs and settings for now.
Comments/Crits would be very much appreciated. Next week, concept comping!
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