SURF: Speeded Up Robust Features: Difference between revisions
No edit summary |
|||
| Line 44: | Line 44: | ||
* 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 (Fig. 2 middle) | ** 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 | **: We have 6 distinct corners so we need 6 fma operations in total for each direction. (Actually 5 if one value is just multiplied by 1) | ||
* 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> | ||
* Pick the direction with the largest vector. | * Pick the direction with the largest vector. | ||