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2-D edge detection using snakes

2-D edge detection using snakes. Project 13 – Team 6. Snakes in general. Snakes or active contours are computer-generated curves that move within images to find object boundaries. Snakes in general. Internal forces (snake attribute) Prevent streching Prevent bending

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2-D edge detection using snakes

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  1. 2-D edge detection using snakes Project 13 – Team 6

  2. Snakes in general • Snakes or active contours are computer-generated curves that move within images to find object boundaries.

  3. Snakes in general • Internal forces (snake attribute) • Prevent streching • Prevent bending • External forces (picture attribute) • Guide towards the object boundaries

  4. Traditional snake • Needs to be initalized close to the object to find it • Can not go into concavities

  5. Gradient Vector Flow (GVF) snake • Can go into concavities • Can be initialized anywhere, even across boundaries

  6. Gradient Vector Flow (GVF) snake

  7. The team • Renáta Hodován – assistance, QA • Ferenc Nasztanovics – homepage • Julian Stottinger – MATLAB • István Vincze – C++ • Péter Siklós – presentation

  8. Original plan Found a semi working GVF snake in MATLAB (original program by Dejan Tomazevic) Had a working C++ GUI but without any force powers (by István Vincze) Extract the snake force features from the MATLAB program, and reimplement in C++, then add some extra fetures

  9. The C++ program • Developement of the internal snake energies • Improvements in GUI functionality • Iteration and snake movement • Calculation of snake direction • Optimalization of snake energy • Tuning internal energies • Embedding the GVF funtcion

  10. „Plan B” C++ program not coming along, so: • Try some features in the MATLAB program • Both programs use the same function to calculate GVF, so results shouldn’t be so different • Save some time experimenting in C++

  11. MATLAB experimentation Wanted to do a snake finding the edge of the team on a group photo

  12. MATLAB experimentation Some holes were not accessible

  13. MATLAB experimentation Reproduced the problem on a smaller image

  14. MATLAB experimentation Conclusion: This problem can not be solved with the traditional GVF snake Some new energies need to be introduced, to force the snake into these kind of cavities. • Readjust snake using tracing quadtrees (see presentation on thermal video processing by András Hajdu) • Contour optimization • Snake area minimalization?

  15. MATLAB experimentation Importance of parameter tuning: Small blur High blur

  16. C++ program results Team photo Lung This is an ugly formula

  17. Thank you for your attention!

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