Linear system based, qualitative independent motion detection from compressed MPEG surveillance video
First Claim
1. A method for detection of independent motion of a plurality of objects presented in a plurality of images acquired at different spatial positions, comprising:
- a) processing each of the plurality of images with an automated processor to generate a respective linear system representing the plurality of objects in the form of a matrix having at least three dimensions stored in a memory;
b) analyzing a plurality of matrices with an automated processor to qualitatively determine whether there is a unique solution for the plurality of matrices as representing a respective linear system, based on a ratio of a singular value decomposition of a matrix with respect to an associated augmented matrix, wherein;
{dot over (x)}+θ
{dot over (y)}+α
x+β
y+y=0represents a linear constraint for each point at coordinates (x,y) with derivatives {dot over (x)}, {dot over (y)}, represented in respective images, wherein α
, β
, γ
, and θ
are functions of both the motion parameters and affine transform parameters between respective images; and
c) outputting a signal corresponding to the qualitative determination, representing whether or not there is independent motion between the plurality of objects represented in the time sequence of images.
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Abstract
The present invention features a qualitative method to detect independent motion revealed in successive frames of a compressed surveillance MPEG video stream using linear system consistency analysis without decompression of the stream, identifying the segments containing independent motion in a real-time or faster manner, for the retrieval of these segments. The linear system is constructed using the macroblocks of MPEG compressed video frames. The normal flow value of the macroblock is obtained by taking the dot product between the macroblock gradient vector, computed by averaging the four block gradient vectors, and the motion vector of this macroblock. The normal flow value is filtered for inclusion in the linear system, and the statistic of the matrices of the resulting linear system is determined, filtered to screen out false negatives and outliers, and used to determine the presence or absence of independent motion.
155 Citations
20 Claims
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1. A method for detection of independent motion of a plurality of objects presented in a plurality of images acquired at different spatial positions, comprising:
-
a) processing each of the plurality of images with an automated processor to generate a respective linear system representing the plurality of objects in the form of a matrix having at least three dimensions stored in a memory; b) analyzing a plurality of matrices with an automated processor to qualitatively determine whether there is a unique solution for the plurality of matrices as representing a respective linear system, based on a ratio of a singular value decomposition of a matrix with respect to an associated augmented matrix, wherein;
{dot over (x)}+θ
{dot over (y)}+α
x+β
y+y=0represents a linear constraint for each point at coordinates (x,y) with derivatives {dot over (x)}, {dot over (y)}, represented in respective images, wherein α
, β
, γ
, and θ
are functions of both the motion parameters and affine transform parameters between respective images; andc) outputting a signal corresponding to the qualitative determination, representing whether or not there is independent motion between the plurality of objects represented in the time sequence of images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for detecting independent motion of an object represented in a plurality of images acquired at different spatial positions, comprising:
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a) at least one automated processor configured to process each of the plurality of images with an automated processor to generate a respective linear system representing the plurality of objects in the form of a matrix having at least three dimensions, and to store the generated matrix in a memory; b) at least one automated processor configured to retrieve a plurality of matrices from the memory, and to analyze a plurality of matrices to qualitatively determine whether there is a unique solution for the plurality of matrices as representing a respective linear system, based on a ratio of a singular value decomposition of a matrix with respect to an associated augmented matrix, wherein;
{dot over (x)}+θ
{dot over (y)}+α
x+β
y+γ
=0represents a linear constraint for each point at coordinates (x,y) with derivatives {dot over (x)}, {dot over (y)}, represented in respective images, wherein α
, β
, γ
, and θ
are functions of both the motion parameters and affine transform parameters between respective images; andc) an output port configured to produce a signal corresponding to the qualitative determination, the signal representing whether or not there is independent motion between the plurality of objects represented in the time sequence of images. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method of detecting independent motion in a plurality of stream of digitally compressed video data, the steps comprising:
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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 the 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 a ratio of a singular value decomposition of a matrix D with respect to an associated augmented matrix Db, to determine a Rank; and d) comparing the respective Ranks of a plurality of matrices D to determine independent motion therebetween, wherein;
{dot over (x)}+θ
{dot over (y)}+α
x+β
y+γ
=0represents a linear constraint for each point at coordinates (x,y) with derivatives {dot over (x)}, {dot over (y)}, represented in the digitally compressed video data, wherein α
, β
, γ
, and θ
are functions of both the motion parameters and affine transform parameters between respective frames of the digitally compressed video data. - View Dependent Claims (19, 20)
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Specification