3d digital platform development to analyze 3d digital...

C.P. GUIMARÃES, 3D Digital Platform development to analyze 3D digital human models. A case of study of Jiu-Jitsu combat Sport.

*Corresponding author. Email: [email protected] 1

3D Digital Platform development to analyze 3D digital human models. A case of study of Jiu Jitsu combat sport

C. P. GUIMARÃES † and F. RIBEIRO † G.L. CID and P. STREIT‡ and J. OLIVEIRA† and M.C .ZAMBERLAN† and A.G.PARANHOS† AND F. PASTURA†

† Instituto Nacional de Tecnologia

‡ Universidade Estadual do Rio de Janeiro

Abstract

The purpose of the study is to present a 3D Digital platform that has being developed in a game engine software to work with motion capture analysis using data captured by Xsens system, IPI studio/kinetics System or any other mocap system and has being applied to the study of Jiu-jitsu. This platform has being developed considering the need to analyze data from the same athletes movements being repeated in different time or even to compare and supplement the same athletes movements being captured with different mocap systems. The main 3D Digital Platform advantage is its flexibility to handle motion capture data from different mocap systems in order to facilitate kinematic analysis by users of motion capture system. The 3D platform development follows some specific steps, which make it possible not only to visualize the performed motion but also turn possible the interaction between the user and the 3D character. The first step consist on the automatically reconstruction of the 3D character body segments based on motion capture data. The visual representation has as benefit the reduced noise that may be generated in the process of retargeting the motion capture data to a specific rig and character that differs from the actual bone structure original data. The visual representation is generated based on Xsens data. This makes the representation being a precise copy of original bone position and structure of the specific actor's movements being captured. The second step is linking each bone segment of the procedurally by generating 3D model with a collision area that is necessary for future interaction with user. After those steps, the user can select : a specific body segment to track and generate data; to play/pause motion; to build a graph of segmental angles, joint angles and angular velocity. These functionality is still under development and tests. The first application of this 3D digital platform was analyzed the Jiu-Jitsu athletes’ movements. This analysis allowed studies and improvements of athletes’ performance. In the future the integration between a 3D scanned athlete’s model and a virtual environment will permit development a virtual simulator that can be applied to education, training and entertainment.

Keywords: 3D Digital Platform, Digital Human Modeling, Mocap, Jiu Jitsu sport

1. Introduction

A digital human model (DHM) is a digital human representation in 3D space that can be moved and manipulated to simulate real and accurate movements of people (Guimarães et al, 2012). Digital human modeling and simulation play an important role in product design, prototyping, manufacturing, sports biomechanics, and many other areas (Guimarães et al, 2010). They reduce the number of design iterations and increase the safety and design quality of products. In order to understand how specific movements are performed, it is important to describe the specific movement under consideration with high accuracy. The motion capture process can be understood into two data structure: the first is to capture the raw data that is characterized by noisily structure while the second is to

present this data in a meaningful structure by mathematical processing (Engel et al, 2010) One main goal of the 3-D motion capture and analyses in sport is the assessment of high-level athletes’ movements in order to define the specific gestures corresponding to highest performance and to prevent the athlete from injury. Assets and drawbacks of these movements can only be understood, if it is possible to describe movements with close-to-reality. The purpose of the study is to present a 3D Digital platform that has being developed in a game engine software to work with motion capture analysis using data captured by Xsens system, IPI studio/kinetics System or any other MOCAP system and has being applied to the study of Jiu-jitsu combat sport. The choice of jiu-jitsu was made based on the assumption that Brazilian jiu-jitsu (Renzo, 2003, Correia


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and Franchini, 2010)) has been an emerging sport in all around the world.

2. Materials and Methods

The methods to platform developing involved four steps that are describing below:

- 1rt step: Scanning the athletes and motion capture – That step was realized at ergonomic labs. The athlete was scanning at WBX scan (Figure 1) and after that the scan was processing to minimize the number of polygons from the raw data and to close the roles – retopology process (Lerch et al, 2007). For the motion captured session the athlete dress a special suit from Xsens with 17 inertial sensors (Figure 2). The athlete selected some jiu-jitsu movements to be collected (Figure 3)

Figure 1 –Jiu-Jitsu Athlete Scanning (Luanna Alzuguir

Athlete )

Figure 2 –Preparing to capture session (Luanna Alzuguir

Athlete )

Figure 3- Jiu-jitsu Motion Capture

- 2nd step: 3D Simulation and Modeling – the data captured from XSENS and the 3D DHM from scan were incorporated to a virtual platform that has been developed at serious game software. The visual representation of 3DHM at the platform was generated based on Xsens data, following position and dimension of bone segments of the virtual body. This makes the representation a precise copy of original bone position and structure of the specific actor's movements being captured

- 3rd step – Developing the Platform - using Unity3D game engine, a tool specialized in motion capture analysis based on motion capture data generated from Xsens, iPiStudio or other Mocap solutions was developed. This platform has been developed considering the need to analyze data from the same athlete movements being repeated in different moments (Kinematics analysis), or even to compare the same movement being captured with different methods/systems. When the same movement is being captured using different motion captured systems, the comparisons between them allow the analyses of the difference in movement curves (Roemer, 2010). The first step consist on the automatically reconstruction of the 3D character body segments based on motion capture data generated on early stages (figure 4). The creation of this visual representation has as benefit the reduced noise that may be generated in the process of retargeting the motion capture data to an specific rig and character that differs from the actual bone structure originally within data. The second step is linking each bone segment of the procedurally generated 3D model with an collision area that is necessary for future interaction with users (figure 5).


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Figure 4 – Visual representation based on motion capture data

Figure 5 - Collision area generated for each bone segment

- 4Th step –Data analysis – the platform allow the kinematic data be visualized by means of graphics – angular and linear position, angular displacement, and angular velocity. The graphics information can also be visualize with with the 3D digital human model. This kind of visualization makes easy to analyze the data with the athletes and coaches. (Figure 6). The data can be export to spreadsheet to be processed.

Figure. 6 – 3D Kinematic data visualization

3. Conclusion

This platform has been testing with different Jiu-jitsu movements captured by using different motion capture system in order to supplement data between motion capture analyses. This analysis allowed studies and improvements of athletes’ performance. In the future the integration between a 3D scanned athlete’s model (Figure 7) and a virtual environment will permit development a virtual

simulator that can be applied to education, training and entertainment (Figure 8) (Souza et al, 2011).

Figure 7 – 3D athlete scanner (Luanna Alzuguir

Athlete )

Figure 8 – Simulator prototype

Acknowledgement

This study has been supported by FAPERJ – Rio de Janeiro Research Government Agency. The researchers would like to thank the athlete Luanna Alzuguir, World Champion Jiu-jitsu for being taking part of the research.

References

CORREIA, W. R. E FRANCHINI, 2010 E. Produção acadêmica em lutas, artes marciais e esportes de combate Motriz, Rio Claro, v.16 n.1 p.01-09, jan./mar. ENGEL K., HERPERS R., HARTMANN U. 2010 Biomechanical Computer Models http://cdn.intechopen.com/pdfs/22188/InTech-Biomechanical_computer_models.pdf GOMIDE, J. V. B, FLAM, D. L , PACHECO, D.; ARAÚJO, A.A. 2009 Captura de Movimento e Animação de Personagens em Jogos VIII Brazilian Symposium on Games 2nd Digital Entertainment Rio de Janeiro, RJ – Brazil, October, 8th-10th


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GUIMARÃES, C. P., CID, G. L., PARANHOS, A. G., PASTURA, G. C. H., FRANCA, G. A. N., SANTOS, V., ZAMBERLAN, M. C. P. L., STREIT, P., OLIVEIRA, J. L., CORREA, T.G.V. 2012. Ergonomic Work Analysis Applied to Chemical Laboratories on an Oil and Gas Research Center. In: Vincent G. Duffy. (Org.) Advances in Applied Human Modeling and Simulation. 1ed.Boca Raton: CRC Press, 2012, v. 1, p. 471-477. GUIMARÃES, C. P., PASTURA, F. C. H., PAVARD, B., PALLAMIN, N.,CID,G., SANTOS,V., ZAMBERLAN, M.C.P.L. (2010) Ergonomics Design Tools Based on Human Work Activities, 3D Human Models and SocialInteraction Simulation IHX Congress, Miami. LERCH, T.L., MACGILLIIVRAY,M., DOMINA, T. 2007 3D Laser scanning: A model of Multidisciplinary Research, Journal of Textile and apparel, Technology and Management, vol. 5, Issue 4, p. 1-22 RENZO, G. 2003 Brazilian Jiu Jitsu. Rio de Janeiro: Ed. Ouro, ROEMER, K. 2010 Biomechanical Modeling Applied to Human Movement Analysis XXVIII International Symposium of Biomechanics in Sports, Marquette, MI, USA, p.23-26 SOUZA, J.M. C.; FAIM, F. T.; NAKASHIMA, I. Y.; ALTRUDA, C. R.; MEDEIROS, W. M. E SILVA,L. R. 2011 Lesões no Karate Shotokan e no Jiu-Jitsu - trauma direto versus indireto, Rev Bras Med Esporte vol.17 no.2 São Paulo Mar./Apr.

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