Shape Tracker


Product: Autodesk Lustre 2008


The separation of objects in moving images is an essential problem in digital post production. During digital color grading for instance colorists have to isolate actors or objects from their background all the time in order to apply some effect only on them. In case of a solid color background - like a green/bluescreen shot - color keying is the technique to use. However, regular shots have usually some arbitrary background, making it impossible to use the keyer. In such cases the colorist - or his/her assistant - has to draw a shape around the object and adjust it frame-by-frame so it stays on the target all the time. This is always a very time consuming thing to do, especially in case of multiple objects and 1000 frame shots...

Lustre 2008 Region Tracker
Footage courtesy of: homenyc & The Video Lab. Click here for more.

During the development of the 3D tracker I have implemented a number of algorithms (automatic detection, tracking and filtering of multiple feature points) that seemed to be a good base for developing an "automagical" object tracker. With the help of my Montreal colleague Jean-Francois Duchesneau we introduced the new Region Tracker in Lustre 2008.

Lustre Shape Tracker Lustre Region Tracker
Lustre Shape Tracker Lustre Object Tracker
Automatically tracking a shape. (Footage courtesy of: homenyc & The Video Lab)

The main idea is to automatically detect a number of feature points (a "cloud" of points) and track them over a number of frames. Using the motion data of all these points (could be multiple hundred!) the motion of the object can be robustly estimated. This means that minor problems - such as partial occlusion - do not interfere with the analysis. Even though we still have to solve a number of issues the feedback is really positive from costumers!
... Brett was eager to demonstrate another new feature: Lustre has a new 3D tracker. It is really outstanding, and I could have sworn we were looking at Imagineer\u2019s tracking technology. Basically you draw a shape around the object you want to track, and it will then go off and track every pixel in the region, adhering to both scaling and rotation of the image content- and pretty quickly too. And that\u2019s not all- it will even track through crossing objects. Brett showed me a shot that trucks sideways, tracking a girl sat on a window ledge. When a tree in the foreground obscures the girl for a few frames, Lustre happily picks up the tracking smoothly without any issues.

Everyone should buy Lustre just for this

says Brett. ...

Lustre Object Tracking Lustre Region Tracking
Footage courtesy of: homenyc & The Video Lab. Click here for more.