Apr 6, 2009

boujou Tracking

So the automatic tracking in Boujou is pretty good but not perfect. It is great for attempting to track everything and anything in the frame (or the mask field) by attempting tons of points. The problem occurs when most of these points only track for a few frames. A movie, 600 frames in length would have about 19000 tracked points. One way to mend this is to stitch tracks together. If you are attempting to track a specific point, chances are that it has been tracked for 95% of the movie. There are multiple tracks that make up the complete path of the track, and it is quite easy but a little time consuming to stitch tracks together. Though time consuming, these composite tracks are now regarded as more accurate than the other ones, so you can track the features again more accurately once you have composited tracks.

But how can we use these points?

There are 3 ways to export usable data from Boujou.
First, Export Feature Tracks: creates a .txt file that has, for each track_id, what frame it is active and its X and Y position. here is some sample data:

# track_id view x y
auto_18604 0 656.968 25.4732
auto_18604 1 669.579 16.3805
auto_18604 2 671.129 15.7436
auto_18604 3 671.787 16.1741
auto_18605 0 213.145 193.769
auto_18605 1 213.142 194.029
auto_18605 2 212.903 194.239
auto_18605 3 215.941 197.151

above are the tracks for points "auto_18604" and "auto_18605". Both are visible in frames 0, 1, 2, and 3. For each of those frames, there is the x and y position.

This method can also export the data for manually placed locators that track user defined points.

Method #2, Export Camera Solve:
even if you want 2D data, not 3D, you could run a camera solve so that the points it generates will last throughout the entire duration of the clip. You will not lose any work you put into the feature tracks (such as if you joined tracks together for a more accurate and longer solve) because these "gold tracks" heavily influence the camera solve it puts out.
Another plus about Exporting a camera solve is that it can be exported as a .ma file to import directly into Maya.

Method #3, Export Tracks to Shake:
This process will simply take all of your Feature Tracks (target tracks and locators as well if you have them) and export into shake as simple 2D movement. I haven’t explored this option fully yet but think it has potential.

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