Problem: SVM training is expensive – Mining for hard negatives, bootstrapping Solution: LDA...
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Transcript of Problem: SVM training is expensive – Mining for hard negatives, bootstrapping Solution: LDA...
Problem: SVM training is expensive– Mining for hard
negatives, bootstrapping
Solution: LDA (Linear Discriminant Analysis). – Extremely fast
training, very similar performance
Claim
Linear Discriminant Analysis (LDA) Assumptions
Learning - Classification
ImplementationFeatures
a simple procedure that allows us to learn a and a (corresponding to the background) once, and then reuse it for every window size N and for every object category.
Implementation
Mean
Covariance
Regularization
• Very large
• In my experiments 10, for making sure that is PSD.
Covariance
Fast training using LDA
Use in clustering
Clustering in WHO Space
Clustering in WHO Space
HOG WHO
Clustering in WHO Space
HOG WHO
(a) SVM
Pedestrian DetectionLinear Discriminant Models
SVM
LDA
Cen
Pedestrian DetectionLinear Discriminant Models
Results
Results
Method Mean AP Train complexity
Test complexity
ESVM + Co-occ 22.6 High High
ESVM + Calibr 19.8 High High
ELDA + Calibr 19.1 Low High
Ours full 21.0 Low Low
Results
Pascal NN Classification
Summary
• Whitened for HOG is better than HOG
• LDA for fast training of hog templates– Object Independent Background (?)
• mean better represents the cluster compared to the medoid– Use all the samples rather than 1
• Their statistical models also suggest that natural image statistics, largely ignored in the field of object detection, are worth (re)visiting.