Interpretation of Motion Trajectories using Focus of Expansion

Authors:
Krishnan Rangarajan;Mubarak Shah
Affiliations:
-;-
Venue:
IEEE Transactions on Pattern Analysis and Machine Intelligence
Year:
1992

Citing 2
Cited 1

A direct method for locating the focus of expansion

Computer Vision, Graphics, and Image Processing
Measuring visual motion from image sequences

Measuring visual motion from image sequences

Two-frame structure from motion using optical flow probability distributions for unmanned air vehicle obstacle avoidance

Machine Vision and Applications

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Abstract

The focus of expansion (FOE) of a group of motion trajectories is defined to be a point in the image plane at which the trajectories intersect when they are extended. The FOE observed over a time sequence defines the locus of the FOE. The authors present an analytical approach for the study of dynamic events as they project on the image plane by analyzing the locus of the FOE. They find that the locus of the FOE can be used to make qualitative assertions regarding the type of motion. Interesting behavior of the locus of the FOE for various types of motion is observed. The cases include a single point and a horizontal, a vertical, and a sloped straight line. It was also possible to determine whether the object has approaching or receding motion or when the object changes its direction of motion. This inference can be used in qualitative computer vision.