The document discusses markerless motion capture. It outlines goals of identifying major body parts, tracking them over frames, and passing the body state to another system. It then describes methods for finding limbs like the arms and legs by looking for joints like the elbows and storing limb length and orientation information. Issues uncovered include determining arm orientation and gaps in the tracking between frames.

1. Markerless Motion capture frances le august 20, 2008 presented by

2. Goals for this project

3. » Identify major body parts. » Track them. » Update the state of the body at next frame. » Pass the state to Carley.

4. What do all these limbs have in common?

5. » In 2D, the lengths and widths of a limb are constant. » A joint can be found a certain distance from another joint on the same limb in any given frame. » Certain joints such as the shoulder or the middle of the spine do not move very much.

6. Finding Major body parts

7. how i find the bird » look for the highest leftmost point. » find the vector tangent to the body contour curve at that point. » identify the vector perpendicular to that tangent vector. » discover the point (which is generally near the elbow) that best fits the line represented by the perpendicular vector. (and the elbow)

8. » find the point closest to first elbow point found. other elbow points

9. other elbow points » find the point closest to last elbow point found starting from the tip of the hand going counter-clockwise.

10. » find the point closest to second elbow point found starting from the last elbow point going counter-clockwise. other elbow points

11. finding limb info » for each point counter-clockwise from the tip of the hand, we find a point perpendicular to its tangent.

12. » for each point counter-clockwise from the tip of the hand, we find a point perpendicular to its tangent. » both the distance between the two points and their median coordinates are stored. finding limb info

13. » for each point counter-clockwise from the tip of the hand, we find a point perpendicular to its tangent. » both the distance between the two points and their median coordinates are stored. finding limb info

14. » for each point counter-clockwise from the tip of the hand, we find a point perpendicular to its tangent. » both the distance between the two points and their median coordinates are stored. » in addition, we find the vector that best fits the middle points. finding limb info

15. » for each point counter-clockwise from the tip of the hand, we find a point perpendicular to its tangent. » both the distance between the two points and their median coordinates are stored. » in addition, we find the vector that best fits the middle points. » we do this for both the forearm and the upper arm. finding limb info

16. finding joint info » we keep the location of the joint. » we also keep the angle.

17. Problems unsolved

18. the upside down arm » range of cos -1 function requires us to know something about the orientation of the arm. » animation needs to know orientation of the arm.

19. we have gaps

20. Fin (for now)