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MediaICE. Optical Flow Through Mechanical Eyes Kim Min Hyun Pua Jun Hong. Overview. Understanding Optical Flow Optical Flow Estimation Techniques Applications of Optical Flow. Overview. Understanding Optical Flow Optical Flow Estimation Techniques Applications of Optical Flow.

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  1. MediaICE Optical Flow Through Mechanical Eyes Kim Min Hyun Pua Jun Hong

  2. Overview • Understanding Optical Flow • Optical Flow Estimation Techniques • Applications of Optical Flow

  3. Overview • Understanding Optical Flow • Optical Flow Estimation Techniques • Applications of Optical Flow

  4. Understanding Optical Flow What is optical flow? • Apparent visual motion • Relative between viewer and the world • Used by insects and animals to navigate the world

  5. Understanding Optical Flow Representing Optical Flow • Represented as 2D vector field • Relationship with motion field • Focus of expansion

  6. Overview • Understanding Optical Flow • Optical Flow Estimation Techniques • Applications of Optical Flow

  7. Estimating Optical Flow Three Main Techniques • Block-Based Methods • Phase Correlation • Gradient-Based Methods

  8. Estimating Optical Flow Block-Based Methods • Basis of MPEG compression • Compare regions (blocks) of pixels in one frame with regions of another frame • Disadvantages • Inaccurate • Prediction errors • Advantages • Fast • Hardware implementable

  9. Estimating Optical Flow Phase Correlation • Most popular Frequency Domain-Based Correlation method • Compare regions in frequency domain • Disadvantages: • Not suitable for periodic images • Computationally intensive • Advantages: • Hardware implementable • More accurate and noise-resistant

  10. Estimating Optical Flow Differential Method • Basic Equation: • u and v are optical flow component in x and y direction • Ix, Iy, It are partial derivatives of image brightness- Image(x,y,t) • However, Optical flow cannot be estimated from this equation! (Aperture Problem)

  11. Differential Method Aperture Problem

  12. Differential Method LK Method • This system can be solved by LMS(Least Mean Square).

  13. Differential Method Bouguet’s Method • Decompose images into the different scales of resolution • Avoids.. • low sampling rates • aliasing effects

  14. Eliete’s Method • Bigger window for the brightness conservation + randomly choosing pixels Using color information • Kelson et al.(2008) - 30% more amount of valid estimated measures

  15. Overview • Understanding Optical Flow • Optical Flow Estimation Techniques • Applications of Optical Flow

  16. Applications of Optical Flow Areas of Interest • Cinematic Special Effects • Autonomous Vehicles • Future Developments

  17. Applications of Optical Flow Cinematic Special Effects • Smoothing and retiming shots • The Matrix: bullet-time sequences • Integration of real and artificial elements • What Dreams May Come: painted world

  18. Applications of Optical Flow Autonomous Vehicles • Learning from insects • Examples: • Hovering and maintaining altitude • Avoiding obstacles

  19. Applications of Optical Flow Facial Expressions • Emotion vector maps

  20. Applications of Optical Flow Gesture Recognition

  21. Demos and Implementation Demos • Manipulate Virtual Object using optical flow • Fluid dynamics • Actor Tracking Using optical flow Implementation

  22. Question and Answer Recap of material covered • Understanding Optical Flow • Optical Flow Estimation Techniques • Applications of Optical Flow

  23. MediaICE Optical Flow Through Mechanical Eyes Thank you for your kind attention.

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