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3D Fingertip and Palm Tracking in Depth Image Sequences. Hui Liang , Junsong Yuan and Daniel Thalmann. Proceedings of the 20th ACM international conference on Multimedia 2012. Outline. Introduction Related Work Proposed Method Experimental Results Conclusion. Introduction.
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3D Fingertip and Palm Tracking in Depth Image Sequences Hui Liang, JunsongYuanand Daniel Thalmann Proceedings of the 20th ACM international conference on Multimedia2012
Outline • Introduction • Related Work • Proposed Method • Experimental Results • Conclusion
Introduction • Human hand is an essential body part for human-computer interaction. • The positions of tracked fingertips: gesture estimation • Difficulty in fingertip tracking: Side-by-side Bending Nearby
Introduction • Many previous methods: • Only focus on extracting 2Dfingertips • Cannot track fingertips robustly for a freely moving hand • In this paper: • Present a robust fingertip and palm tracking scheme • With the input of depth images (KINECT) • Track the 3D fingertip positions quite accurately
Related work • Focus only on 2D fingertips:[4][5][6][9] • Based on contour analysis of the extracted hand region:[2][4][5][6] • Usually can track the fingertips for only stretched fingers.
Related work • In [6], • Fingertips are tracked for infrared image sequences. • It utilizes a template matching strategy • Fingertip tracking : Kalman filter • In [2], • Stereoscopic vision is adopted • Maximize the distance center of gravity of the hand & the boundary
[9] J. L. Raheja, A. Chaudhary, and K. Singal. Tracking of fingertips and centres of palm using kinect, 2011. Proc. Of the 3rd Int’l Conf. on Computational Intelligence, Modelling and Simulation. Related work • In [9] (Kinect), Minimum depth Depth < Threshold Circular filter
Related work • [2] S. Consei1, S. Bourennane, and L. Martin. Three dimensional fingertip tracking in stereovision, 2005. Proc. of the 7th Int’l Conf. on Advanced Concepts for Intelligent Vision Systems. • [4] K. Hsiao, T. Chen, and S. Chien. Fast fingertip positioning by combining particle filtering with particle random diffusion, 2008. Proc. IEEE Int’l Conf. on Multimedia and Expo. • [5] I. Katz, K. Gabayan, and H. Aghajan. A multi-touch surface using multiple cameras, 2007. Proc. of the 9th Int’l Conf. on Advanced concepts for intelligent vision systems. • [6] K. Oka, Y. Sato, and H. Koike. Real-time tracking of multiple fingertips and gesture recognition for augmented desk interface systems, 2002. Proc. IEEE Int’l Conf. on Automatic Face and Gesture Recognition. • [9] J. L. Raheja, A. Chaudhary, and K. Singal. Tracking of fingertips and centres of palm using kinect, 2011. Proc. Of the 3rd Int’l Conf. on Computational Intelligence, Modelling and Simulation.
Overview • Stereo images • (Depth map) • Foreground Segmentation • Palm • Localization • Hand • Segmentation • Fingertip Detection • Fingertip Tracking • Fingertips
Hand and Palm Detection • 1) Assume the hand is the nearest object • 2) Constrain global hand rotation by: • : global rotation angle of the hand
Hand and Palm Detection • Foreground Segmentation • Palm • Localization • Threshold the depth frame to obtain the foregroundF: • p : a pixel coordinate • z(p) : depth value (of point p ) • z0 : the minimum depth value • zD : depth threshold • Hand • Segmentation 0.2m foreground F
Hand and Palm Detection • Foreground Segmentation • Palm • Localization • The palm region is approximated with a circle: • pp: the palm center (of point p ) • rp : the radius • Assume that hand palm forms a globally largest blob • Cpequals to the largest inscribed circle of the contour of F . • 2D Kalman filter : reduce computational complexity • Hand • Segmentation
Hand and Palm Detection • Foreground Segmentation • Palm • Localization • Separate hand and forearmbyaline: • 1) Tangent to Cp • 2) Perpendicular to the orientation of the forearm • Orientation of the forearm : • The Eigenvector that corresponds to the largest Eigenvalue of the covariance matrix of the contour pixel coordinates of F • Hand • Segmentation Hand region : FV(2D)→ FD(3D)
Fingertip Detection and Tracking • Constraints on possible fingertip locations: • 1) Only in depth discontinuous region ( in contour Fv) • 2) | Depth(one point) – Depth(neighborhoods) | are important. • 3) Utilize the 3D geodesic shortest path (GSP) Fingertip vs. Non-fingertip Nearby Fingertips
Fingertip Detection • Fingertip detection • Fingertip tracking • Goal: detect all five fingertips in the depth image • Based on three depth-based features • Build a graph G : • Vh : contains of all points within FV (hand contour) • Eh : for each pair of vertices(p,q), 1) they are in the 8-neighborhood of each other 2) their 3D distance is within threshold τ Edge weight : 3D Euclidean distance
Fingertip Detection • Fingertip detection • Fingertip tracking • Calculate Geodesic distance dg(p): • From palm center ppfor each vertex Vh • Dijkstra graph search on Gh • GSP point set Ug(p): • The set of vertices on the shortest path from pp to p • Rectangle local feature RL(p): • Describe the neighborhood of a point p in FV • : ratio of 1s 1cm
Fingertip Detection • Fingertip detection • Fingertip tracking • Calculate Geodesic distance dg(p): 0.4 dg(p) fingertips
Fingertip Detection • Fingertip detection • Fingertip tracking • Fingertip labeling: Nmax=6 j : label :estimate the probability that has the label lj number of GSP points kth GSP point i : fingertip
Fingertip Detection • Fingertip detection • Fingertip tracking • Fingertip labeling:
Fingertip Tracking • Fingertip detection • Fingertip tracking • Build a particle filter for each fingertip • (x, ω) denote a particle • x : 2D position in FV • ω : the particle weight • Constrain the positions of each particle to the border point set UB to reduce the search space
Fingertip Tracking • Fingertip detection • Fingertip tracking • Likelihood function : pre now Geodesic distance / dg(p) GSP points Neighbor depth /
Fingertip Tracking • Fingertip detection • Fingertip tracking • Likelihood function :
Experimental Results ‧Error : Euclidean distance ‧Ground truth : phalanx end point • Quantitative results on synthetic sequences:
Experimental Results • Virtual object grasping:
Conclusion • Using multiple depth-based features for accurate fingertip localization • Adopting a particle filter to track the fingertips over successive frames • Track the 3D positions of fingertips robustly • Great potential for extension to other HCI applications