report 1: optical flow and sift
DESCRIPTION
Report 1: Optical Flow and Sift. Billy Timlen. Lucas Kanade. ( u,v ) = inv(A t A)* A t *F t Derived from f x *u +f y *v = -f t (after taking the partial derivative in terms of each variable x,y,t Analyze the pixels around the point of interest Requires a degree of padding - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/1.jpg)
Report 1: Optical Flow and Sift
Billy Timlen
![Page 2: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/2.jpg)
(u,v) = inv(AtA)*At*Ft◦ Derived from fx*u +fy*v = -ft (after taking the partial derivative in terms of
each variable x,y,t Analyze the pixels around the point of interest
◦ Requires a degree of padding Works for slow motion and small areas
Lucas Kanade
![Page 3: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/3.jpg)
Results
![Page 4: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/4.jpg)
Reduces the original image into different levels◦ Impyramid(image, ‘reduce’)
Computes Optical flow for each level◦ Shifts derivative mask by u and v of prior level
Add the optical flows of each level Should record more detailed results of
motion
Optical Flow with Gaussian Pyramids
![Page 5: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/5.jpg)
Code
![Page 6: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/6.jpg)
Results
![Page 7: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/7.jpg)
Input: 18x18 patch, keypoint and orientation angle Outputs a descriptor
◦ Histogram of orientation magnitudes Results vary according to the Gaussian used (for
smoothing) and the sigma used (which affects the Gaussian)
Sift
![Page 8: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/8.jpg)
Result
![Page 9: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/9.jpg)
Work with different types of masks
Use different forms of interpolation◦ MatLab has their own function
Use another form of rounding the non-integer indices from u and v◦ Gonzalo sent us a bilinear function to look at
What Next?
![Page 10: Report 1: Optical Flow and Sift](https://reader036.vdocuments.mx/reader036/viewer/2022062310/56816133550346895dd08abc/html5/thumbnails/10.jpg)
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