Hi.
The problem you described isn't so easy. There are two main ways to go.
First, if you want to have *exact* matching objects, vector wise. As if the paths were drawn as a result of multiple boolean operations.
There is no automated way to do that I know of. Heard illustrator has a fairly better tool for that, and know of a similar function in a cad program.
The other route is, dealing with the visual appearance -like as you mentioned, using a raster copy to start with.
The result won't be an exact but a fairly good approximation the best, although there are more options here.
Using the trace bitmap as the base of the process, it's good to know how it works. It uses the luminance level of the selected raster image.
For that reason, drawing with distinctive lightness values can be a good start.
Then, if more scans are used, each resulting path is stacked atop eachother with the same edges represented here and there.
It could be avoided if only one scan is used at a time. Which also means you'd need separate raster copies with only the desired parts filled with the darkest tone.
Even if the original source is a raster image, some filtering may be possible to separate one colour.
And if someone knows how, probably it could be automated via an extension. However I'm not familiar with that part.
Can you share a simple example we could test the process?
