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Tracking and its Applications. Tracking is to follow features from one frame to another in an image sequenceThe definition of a feature depends from implementation to implementationTracking finds many real time applicationsSurvelliance systemsDefence applicationsRobotic arm. A Tracking Exampl
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1. Kanade Lucas Tomasi Tracker Ankit Gupta (1999183)
Vikas Nair (1999219)
Supervisor Prof M. Balakrishnan
Electrical Engineering Department
IIT Delhi
2. Tracking and its Applications
Tracking is to follow features from one frame to another in an image sequence
The definition of a feature depends from implementation to implementation
Tracking finds many real time applications
Survelliance systems
Defence applications
Robotic arm
3. A Tracking Example
4. Kanade Lucas Tomasi Tracker
Algorithm proposed by Kanade and Lucas
Definition of a good feature extended by Lucas and Tomasi
Implementation of the algorithm by vision group at Stanford
5. KLT Control Graph
6. KLT Control Graph
7. Select Good Features
Features are dependent on the method
We select those features that can be tracked well
Optimal by Construction
8. Select Good Features
The image is smoothened by convolving with a Gaussian function
The gradient of each window is calculated by convolving it with derivative of Gaussian of sigma
A list of the windows is made
9. Selection
Feature windows sorted according to eigenvalues of G matrix calculated as
G = ?(ggTw)da
Required top features are selected
Minimum distance between features is maintained
10. Properties of G
Above the Image noise level
Well Conditioned
These properties map onto the eigenvalues characteristics
11. Eigenvalue Characteristics
Small, small : Constant intensity profile
Large, small : Unidirectional Pattern
Large, large : Corners, salt-and-pepper textures
12. Constant Intensity Profile
13. Unidirectional pattern
14. Salt-and-pepper features
15. Tracking Mathematically Solution of the equation
G d = e
G = ?(ggTw)da
Where
G : second order weighted gradient matrix (2?2)
e : weighted intensity error (2?1)
d : Displacement Vector(2?1)
g : Gradient matrix(2?1)
16. The Pyramid of Images
17. Tracking
Coarsest resolution tracked first
Starting point for subsequent resolutions
Newton-Raphson iterative minimization between intensities of two windows
18. Tracking stops when
Feature moves by no more than mindist
? is less than ?min
Number of iterations exceed the limit
Feature is out of bounds
Residue is too large
19. Replace Good Features
On the same principle as Select Good Features.
Retains existing features i.e. those being tracked well.
Keeps a minimum distance between the features.
20. Parallelism
The windows can be threaded
The calculation of the G and e
The convolution with Gaussian function
21. Tracking Video
22. Tracking Video
23. Thanks