SURF: Speeded Up Robust Features: Difference between revisions
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===Orientation Assignment=== | ===Orientation Assignment=== | ||
[[File:Surf fig 2.png | thumb | 500px | Figure 2 from the paper]] | |||
* Sample Haar-wavelet responses in x and y-direction at points around each feature | * Sample Haar-wavelet responses in x and y-direction at points around each feature | ||
** Using integral images, only 6 operations are need to compute in x or y direction | ** Using integral images, only 6 operations are need to compute in x or y direction (Fig. 2 middle) | ||
**: We have 6 distinct corners so we need 5 fma operations in total for each direction. | **: We have 6 distinct corners so we need 5 fma operations in total for each direction. | ||
* Using a 360-degree (pivoting) sliding window with radius <math>\frac{\pi}{3}</math>, calculate the sum of all horizontal and vertical responses yielding vector. Note the window moves in increments of <math>\frac{\pi}{3}</math> | * Using a 360-degree (pivoting) sliding window with radius <math>\frac{\pi}{3}</math>, calculate the sum of all horizontal and vertical responses yielding vector. Note the window moves in increments of <math>\frac{\pi}{3}</math> | ||