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FEBRUARY 09, 2004 After Effects Spline Tricks, Part 3
Other times, Auto-trace needs some help In the following 3D animation, the whites of the left face and the black eyes that cross the background 3D image and nix the possibility of using luminance channels (or any other channel) to find separate Auto-traced splines.[an error occurred while processing this directive] Because I created this animation with Maxon's Cinema 4D, I have access to one of C4's render/compositing tools: the Object Buffer Tag. The Object Buffer Tag allows the 3D animator to create separate alpha channels for each object's visible presence in the scene. Because the white and red face objects are different NURBS in the C4 scene, they can each have their own object buffer, resulting in two separate hicon animations that render concurrently with the RGB render. Simply importing the Maxon Object Buffer renders for the white and red faces into AE6 allows for a quick luminance Auto-trace on the separate faces, without having to create multiple passes of Auto-trace and hacking apart the splines. Note: You can select multiple layers to process Auto-trace on, provided you will use the same parameters for all. Now, with several mask shapes in your comp, generated by Auto-trace's deft work on the luma channels of the Object Buffers, you can add any number of effects which call on the spline shapes as reference. Note: After Effects' handles keyframed masks almost as unique shapes, morphing between them (or in the case of Auto-trace's hold keyframes, stepping between them). Unfortunately, the spline to position feature is adversely effected by the introduced animation in the Mask Shape track. You can still use this information if you have some strange experimental design, but convert the hold keyframes to linear first, then copy/paste a few to see your results. AE will treat each closed spline as a separate animation, resulting in several cycling animations. Ug. I used Trapcode's 3D Stroke here, which allows you to choose which mask you want to selectively stroke (or all masks), allows for taper, repetition, 3D rotation and separate camera movement, among other things. There are so many good things about Auto-trace (rev. 1), that it may seem unfair to point out its limitations, but knowing a tools limitations can sometimes be the same as knowing a tools strengths when it comes to managing your time on a project. You can find more information about Adobe After Effects 6, Zaxwerks Invigorator Classic , Trapcode Shine and 3D Stroke and Maxon's Cinema 4D at their respective Web sites. Ko Maruyama is a freelance animator, 3D artist, and co-host of Digital Media Net's After Effects forum. Prev 1 2 Related sites: • AV Video • Creative Mac • Digital Post Production • Digital Producer • Film and Video Magazine • The WWUG Related forums: [an error occurred while processing this directive] 
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