Announcements
Image matching
Harder case
Even harder case
Harder still?
Answer below (look for
tiny colored squares…)
Features
Image Matching
Image Matching
Invariant local features
Advantages of local
features
More motivation…
What makes a good
feature?
Want uniqueness
Local measures of
uniqueness
Feature detection
Feature detection: the math
Small motion assumption
Feature detection: the math
Feature detection: the math
Quick
eigenvalue/eigenvector review
Feature detection: the math
Feature detection: the math
Feature detection: the math
Feature detection summary
Feature detection summary
The Harris operator
The Harris operator
Harris detector example
f value (red high, blue
low)
Threshold (f > value)
Find local maxima of f
Harris features (in red)
Invariance
Scale invariant detection
Feature descriptors
Feature descriptors
Invariance
Invariance
How to achieve invariance
Rotation invariance for
feature descriptors
Multiscale Oriented PatcheS
descriptor
Detections at multiple
scales
SIFT descriptor
Properties of SIFT
Feature matching
Feature distance
Feature distance
Evaluating the results
True/false positives
Evaluating the results
Evaluating the results
Lots of applications
Object recognition (David
Lowe)
Slide 55