Linear system based, qualitative independent motion detection from compressed mpeg surveillance video

A method of detecting independent motion in a stream of digitally compressed video data, the steps comprising:

• a) selecting a pair of video frames from a stream of digitally compressed video data representing a three dimensional scene;
• b) automatically building a linear system representing the three-dimensional scene for said pair of video frames using at least a three-dimensional to two-dimensional affine transform in which parallel lines remain parallel after affine transformation, and a change in camera position with respect to objects represented in the pair of video frames does not render said linear system inconsistent;
• c) automatically analyzing said linear system represented in a matrix D to qualitatively determine the consistency thereof, substantially without quantitatively solving said linear system, based on an equivalence of a respective rank Rank(D) of the matrix D and rank Rank(Db) of an augmented matrix Db, the consistency being represented as a decision;
• and
• d) storing the decision in a memory,
• wherein:
• Dξ=b,
• D
• =
• (
• 1
• y
• .
• 1
• x
• 1
• y
• 1
• …
• …
• …
• …
• 1
• y
• .
• n
• x
• n
• y
• n
• )
• ⁢
• ⁢
• ξ
• =
• (
• θ
• α
• β
• γ
• )
• ⁢
• ⁢
• b
• =
• (
• -
• x
• 1
• …
• -
• x
• n
• )
• ,
• α, β, γ and θ are functions of three-dimensional motion parameters between the pair of frames, and
• the three-dimensional to two-dimensional affine transform parameters which represent the parameters of a linear constraint {dot over (x)}+θ{dot over (y)}+αx+βy+γ=0 for each image point of a respective video frame p at coordinates (x, y) having a time derivative ({dot over (x)}, {dot over (y)}).

An apparatus for detection of independent motion of a plurality of objects presented in a time sequence of images acquired from different perspectives, comprising:

• a) a processor operating on a data flow in at least in real time, to produce a sequence of outputs corresponding to a current image and a prior image, configured to:
• receive and process the current image in conjunction with the previously received prior image, to generate a linear system representing the plurality of objects represented in the images in the form of a matrix D having at least three dimensions stored in a memory;
• analyze the stored matrix D to determine the qualitative consistency of the linear system based on a relationship of respective Rank of the matrix D and the Rank of an augmented matrix Db, substantially without quantitatively solving the linear system and
• output the consistency decision after determination, representing whether or not there is independent motion between the plurality of objects represented in the time sequence of images.