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Video Object Tracking and Replacement for Post TV Production

Video Object Tracking and Replacement for Post TV Production. LYU0303 Final Year Project Spring 2004. Outline. Brief project overview and targets achieved New components added to the proposed system Working principles of individual parts Future work Q & A. Overview.

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Video Object Tracking and Replacement for Post TV Production

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  1. Video Object Tracking and Replacement for Post TV Production LYU0303 Final Year Project Spring 2004

  2. Outline • Brief project overview and targets achieved • New components added to the proposed system • Working principles of individual parts • Future work • Q & A

  3. Overview • Post-TV productionprocesses and changes the content of a video clip • Difficult for computers to process video in a global view • Step-by-step programming enables the computer to “think” more thoroughly

  4. Overview • We have introduced the following parts in the last semester: • Bitmap I/O • RGB <-> HSV converter • Edge detector • Edge equation finder • Translation detector • Texture mapper • New parts have been added in order to increase thefunctionality of the system

  5. Additional Basic Components • The following parts have been added • Graphical User Interface (GUI) • Corner point finder • Video file reader and writer • Video player processor (frame-based) • Improved texture mapper • The following part has been modified • Bitmap I/O • Edge finder • Texture mapper • Removed Equation processor

  6. Graphical User Interface • Although UI is not a main project part, a good GUI can significantly decrease the time needed for processing and program maintenance • Since C++ language is being used, the Microsoft Foundation Classes are adopted to develop the user interface • Provide most of the basic functions needed for information input and output

  7. Graphical User Interface

  8. Corner Point Finder • As we know that processing dots are much faster than processing lines, we may wish to try to find the corner points directly before finding the edge equations • Stick some brightly coloured labels at the corners of the rectangular surface • Can apply on cylindrical objects as well to indicated the curve control points • A simple K-Means method is used to group the points together.

  9. Corner Point Finder

  10. Video File I/O • As we are talking about video processing, it is inevitable to handle video reading and writing • DirectShow interfaces are being used in the project • Able to process any type of AVI video as long as the Window Media Player can play them

  11. Video Player • We need to choose a video renderer that is suitable for our application • To reserve the function of real-time processing and video texture in the future, the Video Mixing Renderer 9 (VMR9) is used • Allows the rendering of more than one video or bitmap on the screen at the same time

  12. Video Processor • Video are sequence of bitmap frames • We capture each video frame and process them in the same way as processing the bitmaps • After a video frame is being processed, we add them to an AVI file • Default video compressor is DivX Mpeg4 encoder (FourCC code “divx”)

  13. Video Renderer Video System Structure

  14. Texture Mapper • A graphics design technique used to wrap a surface of a 3-D object with a texture map • The 3-D object acquires a surface texture similar to the texture map. • Colors, brightnessvalues or altitudes

  15. Texture Mapper Image coordinates Texture coordinates (r,c) (u,v) Mapping function

  16. Scan-line conversion Scanline yk scanning order Scanline yk+1 • line by line • process each pixel on every line for every line

  17. Cylindrical mapping • Mapping cylinders 3 parts: • Surface detection • Orientation determination • Scan-line mapping

  18. Surface detection • Hough algorithm to detect 2 straight edges

  19. Surface detection • Scanning from top to bottom in an orthogonal way • To detect the points shown • These are points where color transition occurs

  20. Surface detection • Model the curve surfaces by ellipses • X2 / a2 + y2 / b2= 1

  21. Orientation determination • Add markers at the edge • Each indicates a specific portion of the texture map

  22. Scan-line mapping • Line by line • From left to right • Problem: need consideration of depth

  23. Scan-line mapping • Solution: Radius and center of the can could be detected. To find the inclined angle. The larger it is, the more texture map is assigned to that pixel. 1 pixel

  24. Scan-line mapping 1st 2nd 3rd 1 pixel Texture scanning is not line by line

  25. Cylindrical mapping

  26. Shadow mapping • Mapping of surface brightness • Retain the brightness of the original surface • Method: • Compute the average brightness of the image surface • Scale down the texture brightness by (avg_bright/256) • Replace the V value of the mapped surface

  27. Shadow mapping

  28. Limitations • Camera distortion • Lines are not parallel

  29. Future Work • Keep the audio data in output file • Enable input to be any video capturing device • Further increase the accuracy of recognition • Allow user to choose an output format • Video texture replacement (e.g. replace one surface of the sample cube with another video clip) • 3D object mapping

  30. Q & A

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