The Glow effect won't work well enough for you?
thanks for the reply,
no, I need to have control over the color and shape of the moving color. any idea?
A screenshot would help.
Here's the deal. In 3DS Max you should be able to export just the slice or a matte from the pie, or a bunch of other things that would help. If you have no access to the file or the app then you have other options.
The first is a procedural matte. If I had a screenshot I could tell you how to do it precisely. Since the apple pie is basically light brown and I have no idea of what color is behind the removed slice I'll have to guess. You may be able to use a copy of the pie layer and use colorama or other tools to generate a matte. Depending on the shot there are all kinds of options.
If a procedural matte doesn't work then your next option is to rotoscope (make the matte by hand) RotoBrush will automate this quite a bit.
Once you have the matte generated then you'll have to track the movement of the apple to keep the center of your color effect on target. This can be accomplished with AE's (CS6) built in Camera Tracker (if there's a lot of movement and perspective changes). Again, we could give you a better answer if we saw the footage. Even a low rez private youTube copy would help.
Here's a procedural matte solution from a stock shot of a sliced apple. I didn't see a stock shot of a pie that would work. Fast blur minimizes the size of the white specs, Colorama is used to generate an alpha channel from the red hue, and Matte Choker is used to clean up the edges a bit. There are a bunch of reflections on the apple that are problematic, but cleaning them up with a little masking would be an easy task. Once you've got this layer cleaned up you can apply your color effects and use tracking to match any movement.
Give something like this a try and let us know how you do.
Thanks for the reply and the great ideas!
With great solutions comes the need for me to better explain myself and what the project is.
I used a pie cut as an analogy for the picture below. It is a 3d rendering representing a cut through the Earth's crust. The object is basically a box. The top of the box is the Earth surface, and the side of the box is a cross section of the earth showing layers of rock. In the middle is a crack, or fault line like the San Andreas fault. An earthquake will occur in the middle of that crack and I want to show the earthquake energy propagating outward from the crack line moving to the edge of the frame and eventually out..
I was going to use a gradient map of colours (red for high energy and falloff of blue for low energy) and have it move on the surface of the terrain AND on the cross section part too, so that they move evenly together on the 3D shape. Using AE, how can I map and animate a colour map on a 3D shape of the Earth cross section, from this image?
There is no way to pull a procedural matte from that image. If the shot moves you are going to need to do some hand Roto and / or some tracking. The best option is to render just the right half of the shot from C4D so that you have something you could use to automatically generate an accurate path using Layer>AutoTrace.
Once you have a path, if you do not have Trapcode Shine, I'd use Stroke and CC light burst. You'll also have to add some color correction to the footage. It's so light that a light burst effect isn't going to show up very well.
Here's what it looks like with that technique.