Polar Express 1) 3DCG 1.1. L. Kovar 4) 2005 SIGGRAPH

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1 10 Summary Motion capturing approach has researched topics of Human Motion Expressions and Facial Expressions, and has been used in the entertainment industries such as movies. Motion capturing using Motion Capture System is one of the most effective motion reconstruction methods as a data-driven approach. In this paper, we propose an approach for creation of hair animation byusing Motion Capture System. The advantage of our approach is that we can reconstruct hair motion byusing only25 hair strands. We attach the motion capture markers on hairs and then hair strands allocate on the head based on the layer model which hair stylists when they actually use to design the human hair style. Since humans have about 100 thousand hairs on their head averagely, it is impossible to attach the motion capture markers on all of hair strands. Therefore, we allocate hairs with the markers at the edge of the layer as represents of layer s hairs. Then, the hairs are interpolated between them. By this means, we achieve the hair motion based on the motion data capturing approach. Key words: motion capture, hair motion simulation, hair animation 1. CG Motion Capturing Approach for Hair Animation by Eiji SUGISAKI (Member),Yousuke KAZAMA,Takahito ISHIKAWA,Masashi SHIRAISHI,Shohei NISHIMURA, and Shigeo MORISHIMA (Waseda Universityshi). CG 398

2 Polar Express 1) 3DCG 3DCG 3DCG CG CG 2),3) 1 Fig. 1 Reference hairstyle designed by a professional beautician (left) and Hair Strands on the mannequin s head with reflection markers (Right) L. Kovar 4) S.I. Park 5) SIGGRAPH 6) 7) 12) 1 13),14) 13) 399

3 ) S. Hadap 16),17) 18) 19) 24) 25),26) VICON 1.5 mm 4 (a) DV 2 CG VICON MX ) Hz VICON iq ver.2.5 C3D 28) (b) 3 Fig. 3 (a) Top View (b) Side View. Layout for Hair Motion Capture 2 Fig. 2 Capture environment 4 VICON MX mm Fig. 4 Vicon s Motion Capture Camera MX40 (Left). A Reflection Marker (1.5 mm in diameter) (Right) 400

4 4.0 m 2.0 m 3.0 m 3(a) (b) 1.0 m mm ALPHA PRO FAN GIANT 1.5 mm ),3) (a) (a) Sections divided by horizontal line. Top: Green Area, Varietals: Yellow Area, Under: Pink Area (b) (b) Sections divided by vertical line (Backside View (left), Front View (Right)) 5 2) p.5 Fig. 5 Sections of Layer Model 5 (a) 5(b) 5(a) 401

5 (a) mm Fig. 7 6 Fig. 6 Allocation of hair strands A hair strand with reflection markers (left). An example of markers for normalization (Right) D 29) Bodyline Scanner ) 402

6 7 3mm (1) V i = M i V 0 (1) V 0 =(V x0,v y0,v z0, 1) M i V i =(V xi,v yi,v zi, 1) V i i Catmull-Rom Spline 8 9 (2) 10 (3) T (v n) m = am + n b m (2) v ( ) V m,n,l (v n) (v m) = a l v v ( (v n) + m ) b l v v ( ) n (v m) ( n + c l + v v v m ) dl (3) v v m n Fig. 8 Fig Modeling Hair Strands from Captured data 9 Fig. 9 Allocating Hair roots 10 Hair interpolation between hair strands 11 Fig. 11 Detection for mis-interpolated hairs by Approximate Model (right)

7 (4) OP = r OP (4) l r l Fig. 12 Example for relocating mis-interpolated hairs outward (left). Result of hair relocation (right) Fig. 13 Result Animation. Left: Comparison between Reference Video Sequence and Our Result (First Frame, 59 th Frame, 75 th Frame). Right: Result of other views (First Frame, 35 th Frame, 64 th Frame) 404

8 ) The Polar Express. com/ 2) Modern Cut Manual, p.107 (2003). 3) OFFCIAL WEB SITE 4) L. Kovar et al.: Motion Graphs,In Proc. of SIG- GRAPH 2002,pp (2002). 5) S.I. Park: Capturing and Animation Skin Deformation in Human Motion,In Proc. of SIGGRAPH 2006, pp (2006). 6) O. Arikan: Compression of Motion Capture Databases, In Proc. of SIGGRAPH 2006,pp (2006). 7) P.G. Kry et al.: Interaction Capture and Synthesis,In Proc. of SIGGRAPH 2006,pp (2006). 8) E. Sifakis et al.: Automatic Determination of Facial Muscle Activations,In Proc. of SIGGRAPH 2005, pp (2005). 9) T. Mukai et al.: Geostatistical Motion Interpolation, In Proc. of SIGGRAPH 2005,pp (2005). 10) V.B. Zordan et al.: Dynamic Response for Motion Capture Animation,In Proc. of SIGGRAPH 2005,pp (2005). 11) L. Ren: A Data-Driven Approach to Quantifying Natural Human Motion,In Proc. of SIGGRAPH 2005, pp (2005). 12) M. Muller et al.: Efficient Content-Based Retrieval of Motion Capture Data,In Proc. of SIGGRAPH 2005, pp (2005). 405

9 ) T. Yotsukura et al.: Construction of Audio-Visual Speech Corpus using Motion-Capture System and Corpus Based Facial Animation,IEICE Transactions on Information and Systems,Vol.E88-D,No.11,pp (2005). 14) Z. Deng et al.: eface: Expressive Facial Animation Synthesis and Editing with Phoneme-Isomap Controls, In Proc. of SCA 2006,pp (2006). 15) K. Anjyo et al.: A Simple Method for Extracting the Natural Beauty of Hair,In Proc. of SIGGRAPH 1992, pp (1992). 16) S. Hadap et al.: Interactive hair styler based on fluid flow,in Proc. of Eurographics Workshop on Computer Animation and Simulation 2000,pp (2000). 17) S. Hadap et al.: Modeling Dynamic Hair as a Continuum,Computer Graphics Forum,In Proc. of Eurographics 2001,Vol.20,No.3,pp (2001). 18) S. Hadap: Oriented Strands - Dynamics of Stiff Multi body System,In Proc. of SCA 2006,pp (2006). 19) J.T. Chang et al.: A Practical Model for Hair Mutual Interactions,In Proc. of ACM SIGGRAPH SCA 2002, pp (2002). 20) Y. Yu: Modeling realistic virtual hairstyles,in Proc. of Pacific Graphics 2001,pp (2001). 21) Y. Bando et al.: Animating Hair with Loosely Connected Particles,In Computer Graphics Forum,Vol. 22, No.3,2003,pp (2003). 22) K. Ward et al.: Adaptive Grouping and Subdivision for Simulating Hair Dynamics,In Proc. of Pacific Graphics 2003,pp (2003). 23) T-Y Kim et al.: Interactive Multi resolution Hair Modeling and Editing,In Proc. of SIGGRAPH 2002,pp (2002). 24) B. Choe et al.: Simulating Complex Hair with Robust Collision Handling,In Proc. SCA 2005,pp (2005). 25) S. Paris et al.: Capture of Hair Geometry from Multiple Images,In Proc. of SIGGRAPH 2004,pp (2004). 26) Y. Wei et al.: Modeling Hair from Multiple Images,In Proc. of SIGGRAPH 2005,pp (2005). 27) VICON Peak Inc., VICON motion capture system iq manual, 28) The C3D web site. 29) CS Motion Capture