I've been busy recording the voice actors for my next film, as well as creating the 3D models I'll need to animate the film. I have all the main characters modeled, but now I need to crank out a bunch of character extras to populate the background shots where they need to be. One of the most time consuming part of modeling characters is to create 'clone' extras and have them not look like clones. This is where scripting and a little trickery with vertex colors comes in handy:
The "extras" are just low poly models rigged with a standard physique/biped rig. The clones are "mesher" objects which duplicate the model, with an added time offset plus or minus time. The idea here is to animate a long sequence (2-3 mins) for the master, then offset the clones by randomly spaced increments to break up any repetitive motions.
To differentiate the clones from one another, I've come up with the material rig above. One material is applied to all the clones, but it uses the Vertex Paint channels to derive the rendered color. By stacking 3 separate vertex color modifiers using "additive" mode: full red, full green and full blue, I can mix any RGB color I want for the clothing of the characters. A separate control for hair color is put on a separate vertex color channel, this blends from black to white, and I use a color curve to get a range of 'hair' colors based on lightness:
In the modifier stack of each clone, I've setup a Morpher modifier which is actually turned off. The morpher is handy because it puts a lot of little sliders in a handy spot, and putting it at the top of the stack ensures that it'll be the first thing that comes up when you select the object; handy for making quick changes. I used the Wire Parameter dialog to link the morph channels directly to the layer visibility of the vertex colors for red, green, blue, and hair color. This lets me quickly change the appearance of each clone.
Now, the model above looks a little distorted, due to the noise modifier I've added to create the 'sketch' effect. In the case of these extras, they are in the background, so a bit of exaggeration on the 'sketch effect' is necessary to blend them into the background. It is common in anime, and animation to have static, motionless background characters in crowd shots, simply because of the amount of time it would take to animate them. (The only film I can think of where they spent a lot of time animating large crowds of people would be Akira...) I've always tried to avoid this, and the 3D animation tool of the computer allows for more lively motion from the background actors. Subtle motion is necessary so as not to distract from the main action. And anything that makes my life easier in this regard is good too.
Well, off to create about 6-8 more 'master' extras and populate the background of my film...