1. Simon Smith Jamie Hutton Thomas Moore David Newman
Gait Recognition
Simon Smith Jamie Hutton
Thomas Moore David Newman

2. Outline Gait? Enrolment Symmetry Hu Invariant Moments Classification
Conclusions
Demonstration

3. Gait? From Old Norse gata for “path” Why use gait as a biometric?
But possibly from Northern derivative of goat
Why use gait as a biometric?
Non-invasive
Process sequence of images
More information than other biometrics
Greater robustness/reliability
Gait recognition methods
Model-based
Holistic approach

4. Holistic Methods Chose to implement two holistic approaches
Less computationally complex, faster
More suitable for online demonstration
A simple representation of Gait
Raw numbers, images
Problems with occlusion, noise

5. Enrolment Capture subject’s gait Process video of subject walking
Video ideally with chroma-key background
Avoid occlusion of subject
Outdoor images cause some problems
Process video of subject walking
Background subtraction
Indoor – Chroma-key, Outdoor – Mixture of Gaussians
Binary silhouette of each frame
~30 frames captures complete gait cycle
Begin at known heel-strike

6. Symmetry Crop and resize images to 64x64 Centre the body in the image
Extract symmetry for each image in sequence
Average all symmetry maps to get Gait Signature
Compare Gait signatures directly + + + =
Number of images

7. Hu Invariant Moments
Shape descriptor, combines moments to give invariance to
Rotation
Translation
Scaling
Originally designed for single shape description, extended here for sequences
We use Hu1, Hu2 and Hu8 moments
Other moments fail to discriminate between subjects

8. Classification k Nearest Neighbours classification Euclidean distance
Up to 6-dimensional feature space
Mean of 1 or all Hu moments
Variance of 1 or all Hu moments
Tie Resolution
Highest ranking matches chosen

9. Conclusions Evaluation of two Holistic Gait descriptors Hu Moments
Good indoor performance
Poor performance outdoor
Needs higher dimensional parameter space
Ability to ignore/correct anomalous results
Symmetry
Good indoor, better outdoor performance
Larger population may cause poor performance

10. Demonstration