Deformable Part ModelDeformable Part Model

Presenter ： Liu ChangyuAdvisor ： Prof. Alex HauptmannInterest ： Multimedia Analysis

April 11st, 2013

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Contents

Introduction Model Learning Experiment Conclusion

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1. Research Question1) Object bank is just a image representation for high-level visual tasks, it should be used combing with detailed efficient traning method.2) For difficult tasks, such as extending Object Bank to over 1000 objects and benchmarks of the PASCAL Challenge, it need new traning method to improve the average precision.3) So we want to combine use the part model that proposed at CVPR in 2008.

Introduction

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2. What’s Deformable Part Model?Deformable Part is a discriminatively trained, multiscale model for image training that aim at making possible the effective use of more latent information such as hierarchical (grammar) models and models involving latent three dimensional pose.

Introduction

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Contents

Introduction Model Learning Experiment Conclusion

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Fig. 1 Deformable Part Model

Model--- Deformable Part

The deformable model include both a coarse global template covering an entire object and higher resolution part templates.The templates represent histogram of gradient features

(b1) coarse template (b2)part templates (b3) spatial model (a) person detection Example

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Fig.2 Pyramids of Deformable Part Model

Model---Deformable Part

Fig.2 illustrates a placement of such a model in a HOG pyramid. The root filter location defines the detection window (the pixels inside the cells covered by the filter). The part filters are placed several levels down in the pyramid, so the HOG cells at that level have half the size of cells in the root filter level.

(b)HOG feature pyramid(a) Image pyramid

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Model---Deformable Parts

The score of a placement is given by the scores of each filter (the data term) plus a score of the placement of each part relative to the root (the spatial term),

Where is the w × h × 9 × 4 weight vector are the features in a w×h subwindow of a HOG pyramid. gives the location of the i-th part relative to the root location. ai and bi are two dimensional vectors coefficients for measuring a score for each possible placement of the i-th part.

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Contents

Introduction Model Learning Experiment Conclusion

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LearningLatent SVMsThis model use Latent SVMs to have a classification. As:

where is a vector of model parameters, needed to be learned first, according to:

z is a set of latent values.

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Contents

Introduction Model Learning Experiment Conclusion

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Experiment

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We execute the matlab code as…..

Experiment

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Contents

Introduction Model Algorithm Experiment Conclusion

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1)Experiment has not completed yet, it needed more object models used for deformable part training.

2) Computation need to be speed up.

Conclusion

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Reference

[1] P. Felzenszwalb, D. McAllester, D. Ramanan. A Discriminatively Trained, Multiscale, Deformable Part Model. IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2008

[2] P. Felzenszwalb, R. Girshick, D. McAllester, D. Ramanan. Object Detection with Discriminatively Trained Part Based Models. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 32, No. 9, Sep. 2010.

[3] Level Image Representation for Scene Classification and Semantic Feature Sparsification. Proceedings of the Neural Information Processing Systems (NIPS), 2010.

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Thank you!Thank you!