Harris Corner Detector
Mathematics
• Change in appearance of window W for the shift [u, v]:
E(u, v) =
(x,y)∈W
[I(x + u, y + v) − I(x, y)]2
• First-order Taylor approximation
I(x + u, y + v) ≈ I(x, y) + Ix
(x, y)u + Iy
(x, y)v
• Let’s plug this into E(u, v)
E(u, v) ≈
(x,y)∈W
[I(x, y) + Ix
(x, y)u + Iy
(x, y)v − I(x, y)]2
≈
(x,y)∈W
I2
x
u2 + 2Ix
Iy
uv + I2
y
v2
NHSM - 4th year: Computer vision - Keypoints (Week 3-4) - M. Hachama (
[email protected]) 9/20