REAL-TIME VISUALIZATION OF WOVEN TEXTILES

MIRALab - Univesity of Geneva, 24 Rue Geneal Dufou, CH1211 Geneva 4, Switzeland adabala@mialab.unige.ch REAL-TIME VISUALIZATION OF WOVEN TEXTILES Neehaika Adabala Nadia Magnenat-Thalmann Guangzheng Fei MIRALab - Univesity of Geneva, 24 Rue Geneal Dufou, CH1211 Geneva 4, Switzeland thalmann@mialab.unige.ch Animation School, Beijing Boadcasting Institute, China gzfei@bbi.edu.cn KEYWORDS Weave Pattens, Illumination Model, Multi-Textuing. ABSTRACT This pape pesents a technique fo visualizing woven textiles in eal time, while optimizing the ealistic appeaance. The poposed appoach suppots endeing of complex weave pattens by adopting Weaving Infomation File (WIF), a standad fom textile Compute Aided Design (CAD) fo epesenting the gamma of weaving. We develop a ealistic endeing scheme by combining the gamma epesentation obtained fom the WIF with a pocedual thead textue, a suitable textile Bi-diectional Reflectance Distibution Function (BRDF) and hoizon maps. We employ the multi-textuing appoach to meet the eal time constaint. Thus ou appoach to visualizing woven textiles begins fom weaving gamma specifications and convets them into textues that can be used fo visualizing clothes. We demonstate the vesatility of the poposed appoach with examples. INTRODUCTION Thee ae two main aspects to the poblem of modelling and simulating textiles: Modelling the dynamics of textiles: Textiles ae flexible and exhibit dynamic behavio when inteacted with. This is an impotant chaacteistic of textiles that has been studied extensively and a lage amount of eseach has been done in the aea of modelling dynamics of clothing in the context of textile eseach (Kawabata 1975; Clapp and Peng 1990; Collie et al.1991; Gan et al 1995; Kang and Yu 1995) and compute gaphics (Volino and Magnenat-Thalmann 1995; Baaff and Witkin 1998). Most of these techniques ae non ealtime, howeve ecent wok (Codie and Magnenat- Thalmann 2002) has made it feasible to simulate the clothing dynamics in eal time. Visualizing textiles: Textiles exhibit mico and macogeomety (we efe to milli-scale geomety as macogeomety in this pape). The light inteaction with the intewoven theads has to be captued in ode to ceate a ealistic appeaance. This pape focuses on the second aspect namely visualizing textiles. Ou goal is to ceate a eal time technique that enables endeing of complex weave pattens. The ability to visualize the appeaance of the textile ealistically is impotant fo the completeness of digital epesentation of textiles. Such digital vitual textiles have application in fashion industy whee compute aided pototyping of clothing is gaining impotance, in e-commece whee an authentic epesentation of eal wold aticles is needed, in clothing fo vitual chaacte, etc. We have chosen to meet eal-time constains in ode to be able to integate ou appoach with clothes designing softwae, which equies the designe to peceive changes immediately. Thee ae two main types of textiles namely, the knit and woven textiles. Impessive esults have been epoted in ecent eseach on visualization of knitwea (Zhong et al 2000; Daubet et al. 2001; Gölle et al 1995; Meissne and Ebehadt 1998; Xu et al 2001). Techniques to epesent complex knit pattens have been developed (Meissne and Ebehadt 1998, Zhong et al 2000). Relatively less wok has been done in the aea of woven textiles, especially in the context of epesenting complex weave pattens. The main issues that have to be addessed when developing a technique fo visualizing textiles ae: Repesentation of intewoven theads Modelling of light inteaction with the theads/ textile. We biefly descibe some of the pevious wok in the light of these issues. Westin et al. (Westin et al 1992) conside a weave patten and obtain ealistic endeing of textile. In this wok they conside a simple altenate weave patten known as the linen binding and model the illumination at micoscale and extend it to the milli-scale by pefoming an integal ove the suface. Yasuda et al. (Yasuda et al. 1992) descibe a shading model fo textiles that emphasizes on the inteaction of light with individual fibes that constitute the textile. Gölle et al. (Gölle et al 1996) use a technique based on thee-dimensional textues to model textiles. Moe ecently, Daubet et al. (Daubet et al. 2001) have pesented an efficient technique fo modelling and endeing clothes, thei appoach is applicable especially fo coasely woven fabic and knitted fabic. Apat fom the wok that diectly addesses the poblems of endeing clothes thee is a class of wok based on light inteaction with sufaces that exhibit mico-geomety that can be applied to addess poblems in endeing of clothes. These include the wok by Ashikhmin et al. (Ashikhmin et al. 2000) that develops a mico-facet based technique fo modelling light inteaction with sufaces and applies it

effectively to simulate the appeaance of velvet and satin. Also the techniques of illuminating mico-geomety descibed in Heidich et al. (Heidich et al. 2000) and Sloan et al. (Sloan and Cohen 2000) find diect application to visualization of textiles as they exhibit mico-geometic details. All the existing techniques ae vey poweful and solve the poblem of visualizing clothes effectively, but the existing techniques do not addess the poblem of being able to captue a wide vaiety of weave pattens. Some vaiations othe than the most common linen binding have been consideed in (Ashikhmin et al. 2000) and (Daubet et al. 2001) whee pattens simila to satin binding ae consideed. Howeve the moe complex ones have not been addessed. The objective of ou technique is to povide clothes and gaphics designes with the capability of geneating textues with vaious designs of weave pattens to textue the clothes designed by them without having to use scans/photogaphs of sample textiles. Appoaches using scans/photogaphs suffe fom the poblem of pesence of featues esulting fom the illumination unde which the images wee geneated. Thus thee is a need to povide textues with the ability to exhibit the change in illumination behavio, without the illumination being incopoated into the colo of the mateial in a fixed way. Also, we would like to zoom in onto the textile and be able to peceive detail. In ode to addess these issues we beak up the poblem of visualizing textiles into: Repesenting the weave patten Modelling the micostuctue of the theads of the textile. Modelling the light inteaction with the textile: o Reflection behavio o Shadowing behavio between the theads in the weave patten. Ou appoach addesses the above issues as follows: We use a standad in the textile industy known as the Weaving Infomation File (WIF) to obtain the complex weaving pattens and epesent pattens suitably fo geneating the colo textue. The micostuctue of the theads is incopoated into a pocedual textue and it is used along with the WIF infomation to geneate a colo textue. The WIF infomation is also used to define a suitable Bidiectional Reflectance Distibution Function (BRDF) that coesponds to the eflection behavio of the textile. The shadowing that occus between the theads when they ae woven togethe is captued in the hoizon maps that ae geneated with infomation fom the WIF. We ae thus able to stat fom the gamma epesentation fo weaving a textile and geneate a visualization of the woven textiles. One of the impotant aspect of the wok is that we not only captue the appeaance based on the weave gamma but we also captue the way light inteacts with the mateial. The oganization of the pape is as follows: the next section an oveview of ou algoithm is given. The details of the fou main pats of ou algoithm ae then descibed. We discuss the esults by pesenting example images that demonstate the capabilities of ou algoithm. Conclusions and suggestions fo futue wok ae given in the final section. OVERVIEW OF THE ALGORITHM The outline of the algoithm is pesented in the Figue 1. Figue 1: Outline Of Algoithm

The algoithm uses the infomation in WIF that descibes the weave patten. It is intepeted by the WIF intepete and made available to the modules namely: the mico-geomety shade, the BRDF geneato and the hoizon map geneato. The mico-geomety shade makes use of a pocedual thead textue geneato to ceate a colo textue based on the WIF. The pocedual thead textue geneato is esponsible fo ceating the shading that esults fom the twisting of the fibes that ae spun into the theads. The BRDF geneato takes as input the chaacteistic of the textile obtained fom the weave patten descibed in the WIF. It geneates a BRDF to coespond to these chaacteistics. The WIF does not contain any popeties that descibe the illumination chaacteistics of the thead, theefoe WIF alone does not give the complete infomation equied fo defining an illumination model. Howeve, the patten of weaving contibutes significantly to the way the light inteacts with a fabic. This is vey well exemplified by the fact that the satin weave esults in textiles with glossy appeaance. The WIF contains the weave gamma and theefoe fom this infomation it is possible to lean which facets of the theads ae longe and hence tend to be highe on the suface of the textile. This in tun dictates how such facets of textile cast shadows on the neighboing theads of the textile. The hoizon map geneato module uses the WIF infomation to define these shadows that ae essential to convey the feeling of depth in the weave patten. The eal time constaint pompted us to use the multi-textuing appoach to ealize the solution to ou algoithm. Each of the above modules esults in a textue and the final endeing of the textile is done by compositing the images suitably. DETAILS OF THE ALGORITHM The fou main modules of ou appoach namely the WIF intepete, the mico-geomety shade, the BRDF geneato and the hoizon map geneato ae descibed in this section. WIF Intepete Woven fabics exhibit well-defined stuctues; it should be possible to use a pocedual o gamma-based technique to epesent the weave patten. Howeve, the wide vaiety of the weave pattens limits the applicability of such techniques. Fotunately, in CAD of textile thee is a wellestablished technique fo epesenting the weave patten as WIF fomat (Nielsen et al. 1997). It is a specification that povides the infomation equied fo weaving a fabic in textile looms. The WIF includes infomation fom which the weave patten can be deived. The patten indicates how wap and theads ae intewoven Since the WIF fomat was designed fo manufactuing pupose athe than fo visualization, it is not diectly applicable to compute gaphics. The WIF contains the theading infomation that defines which wap thead goes though the heddle in which shaft. It also contains a liftplan that epesents the combination of shafts aised fo ceation of each. The weave patten can be obtained by combining the theading and the liftplan infomation. We pase the WIF fomat and deive the weave patten fom it. The weave patten is epesented as a two dimensional matix, whee the ows and the columns can be thought of to index the and wap theads espectively. Each enty in the matix indicates the visibility of the o wap thead at that point. The numbe of and wap theads pesent in the weave patten detemines the dimension of the matix. The WIF fomat also contains colo infomation fo each thead that can be diectly combined with the patten matix to geneate the colo scheme fo the weave patten. Since the weave patten matix indicates which thead is seen at each point on one face of the textile, the textue fo the othe side of the textile is easily obtained by complementing the matix. Figue 2 shows a colo scheme of a complex weave patten geneated fom a WIF fomat. Figue 2: Example Colo Scheme Of A Weave Patten Mico-geomety Shade The woven fabics ae made up of intewoven twisted fibes. We have obseved that when one examines woven textiles at the usual distances of viewing the twisted natue of the thead facets is often visible. The visibility is caused by the pesence of dak shaded lines that follow the twist of the fibes of the thead. In some cases these lines ae seen pominently while in othe cases they ae less pominent. It is possible to discen whethe the theads ae tightly o loosely twisted fom these shaded lines. We also obseved that the shading pesent on the thead facet tends to emain appoximately the same unde vaious lighting conditions. We may attibute this to pesence of deep fine gove between the twists of the fibe into which the light neve eaches. This featue is unlike the othe illumination aspects of the maco-geomety of textiles in the fom of shadowing between the theads that show vaiation with position of light. Also unlike wool whee the fibes occupy a significant volume, the theads that ae woven into a textile ae fine and ae limited to a nea two-dimensional suface. The above obsevations lead us to sepaate the mico and maco-geomety details pesent in the woven textiles. We exploit the nea two-dimensional natue of the textile suface by modelling the facet of thead visible on the suface of a textile as a two dimensional pocedual textue. We design the pocedual textue such that it has paametes to captue the tightness of the twist and thickness of the thead. Figue 3 shows examples of the thead shading textues that ae geneated pocedually by ou technique.

Figue 3: Output Of Pocedual Textue (a) Vey Loosely Twist Of Thead Without Shading. (b) Moe Tightly Twisted Thead, Noise Is Added To Simulate The Pesence Of Fibes About The Thead. (c) Thicke Fibes Twisted Into Thead. (d) Tightly Twisted Thead. These thead textues can be used along with the weave patten to geneate a colo textue of a weave patten that has the appeaance of being woven fom twisted fibes. An example of such a textue is shown in Figue 4 Figue 4: Colo Textue Geneated Fo The Colo Scheme BRDF Geneato The image that is geneated by combining the micogeomety shade and the weave patten does not include an illumination model. It only contains the colos of the theads and the patten of weaving. Howeve, the same weave patten can have a significantly diffeent appeaance based on the mateial of the theads that constitute the textiles. Also, the same theads can esult in a diffeent textue of the textile depending on the weave patten. This has aleady been pointed out befoe when it was mentioned that use of the satin weave patten esults in a moe glossy textue than linen weave patten fo the same quatilty of thead. In ou technique the BRDF geneato makes use of the WIF infomation to define a BRDF. Vaious appoaches to epesent the BRDF can be adopted. We choose the micofacet based BRDF modelling (Ashikhmin et al. 2000) because it is flexible and can be used to model complex eflection behavio. In this appoach design of suitable pobability distibution functions of mico-facet enables modelling of vaious types of textues. We have define a genealization of the fomulation used in fo satin in [1], to epesent the pobability distibution. The pobability distibution of the mico-facets that we use is: p( h) = f * p ( h) f * p ( h) wap wap + whee p(h ) epesents the pobability distibution of the nomals of the mico-facet, f and f ae espectively wap the factions of the suface occupied by the wap and theads. The pobability distibutions of facets on individual wap and theads ae given by the p wap (h) and (h) espectively. The h epesents the nomalized p half vecto between the vecto to the light and the vecto to the viewe. The paametes f and f ae computed wap fom the WIF. Howeve no infomation is pesent in the WIF to enable us to define the pobability distibutions of the mico-facets on individual theads in the wap and diections, namely the functions fo p wap (h) and (h). We use a cylindical Gaussian with σ = p simila to the one descibed in [1] fo this pupose. The width of the thead is used to choose the σ of the cylindical Gaussian. The details fo evaluating the BRDF fom a distibution fo micofacets ae found in (Ashikhmin et al. 2000). The textiles can appea moe biased to the colo of the waps o s depending on the angle of viewing. This view dependence of the appeaance of the cloth is incopoated into the BRDF when the colos that ae woven togethe ae vey contasting with the help of the Fesnel's co-efficient. The co-efficient is computed as a weighted sum as follows: When the angle of viewing is close to pependicula the wap colo is given a highe weight. When the angle of viewing is at gazing angles the colo is given a highe weight. The cosine of the angle between viewing diection and the nomal to the suface is used to compute the weight. This is a heuistic appoach to incopoate the dependence of appeaance on the viewing angle. We achieve the eal-time endeing of the BRDF by using the cube map appoach (Kautz and McCool 1999). The BRDF we use is defined fo the whole textile athe than fo individual thead segments theefoe some details like shadowing of theads on each othe ae not captued by it. These details ae captued in the hoizon maps that ae descibed in the next section. Hoizon Map Geneato Hoizon maps stoe shadows cast by small suface petubations on itself. In the case of fabics in outdoo day light scenes this featue is elatively less impotant as thee is a lage amount of light incident on the fabic fom all diections esulting in the absence of shadowing among theads. Howeve, in the case of atificial lighting in indoo scenes we have obseved that the fabics tend to look significantly diffeent unde lighting and this is due to the shadows cast by the theads on each othe. We obseve that the height of a facet of thead above the textile suface is dependent on the length of the facet on x y

which it occus. Howeve, the height is limited to a maximum level dictate by the tightness of the weave. This height in tun defines the shadow that it can cast on the neighboing thead facets. The WIF infomation in the fom of the weave patten matix is used to compute the length of the facet at each location within the weave. This infomation is then tanslated into a height field that is futhe used to compute the hoizon maps. We discetize the diections of the light and geneate a shadow map fo each of the diections. This appoach is less accuate than the techniques poposed in [7] and [11], howeve we found that it gives easonable esults fo ou eal time constaints. RESULTS AND DISCUSSION This section pesents example images that have been geneated using ou technique. We implement ou algoithm on a PC with a pentium 4 pocesso (2 GHz), with a nvidia gaphics cad. The clothes that have been endeed in this section wee modelled with MIRACloth, the in house softwae of MIRALab fo designing clothes. All the models in the figues consist of appoximately 2000 tiangles each. We pefom the computation of the colo textue, BRDF textue and the hoizon maps as a pepocessing step. The computation time fo the colo textue is less than one second and each of the shadow maps takes about half a second. The BRDF computation along with the sepaation fo cube maps equies aound 140 seconds. The endeing of the images fom these pe-computed textues using multitextuing is achieved in eal-time. We pesent example images of jackets ceated fom vaious weave pattens in Figue 5. Use of the WIF based method enables easy geneation of many complex and inteesting weave pattens. This esult is especially elevant to show that ou technique combines the benefits of developments in both compute gaphics and textile industy. Figue 5: vesatility of the appoach fo geneation of vaious weaves. The jacket on the ight is textued by the weave patten pesented in figue 4. Figue 6: diectional dependence of the appeaance of textile when contasting coloed theads ae woven togethe. The figue 6 shows the powe of ou illumination model. We ae able to captue the vaiation in appeaance of a cloth woven with contasting coloed theads. This is possible because of ou BRDF function that models the detailed light inteaction. This esult is not possible with only textuebased appoaches that ae widely used. The ability to visualize such textiles ealistically gives a designe a cleae pespective of the end poduct of thei design. We demonstate the ability of ou technique to suppot viewing at vaious levels of detail in the Figue 7. It can be seen that ou technique esults in a vey ealistic appeaance of the textile even at close distances. The pesence of shadows enhances the feeling of thickness of the textile.

Figue 7: illustation of ability to zoom in on detail. The image on the top ight gives the weave patten used to textue the dess. CONCLUSIONS AND FUTURE WORK This pape has poposed a technique fo geneating ealistic visualization of woven textiles in eal-time. The main featues of the wok ae: Textue of fabic geneated fom gamma: Such textues ae typically geneated as sample bitmaps with no accompanying illumination model. In ou case we have developed a moe complete epesentation of the textile that also models the light inteaction. As it woks in eal-time it can be used fo visualizing textiles in clothing design. Compatible with textile CAD: Use of the WIF fomat that has been a standad in the textile industy fom 1996, makes ou wok compatible with wok caied out in the textile industy and thus helps to bidge gaps by shaing knowledge between the compute gaphics technologies and textile technologies. Mico and Maco detail sepaation: In ode to meet the eal time constaint and also not lose the details in modelling the cloth, we sepaated details of the cloth visualization into mico and maco details. The mico details wee incopoated into the thead textues that wee geneated pocedually while the maco details wee incopoated into the BRDF and hoizon maps. Weave patten based BRDF: The ability to epesent the weave as a gamma enabled us to define the BRDF based on the patten. Relatively less impotance has been give to this aspect of visualizing textiles in compute aided design tools of the textile industy. Howeve this is of pime impotance fo ealism of the visualization and hee again thee is a bidging of gaps between the two aeas. Woks in eal time: The multi-textuing appoach was exploited to develop an algoithm that woks in eal-time. While the algoithm descibed in the pape gives ealistic esults, the BRDF technique pesented in the pape uses an estimation ove the whole weave patten. Howeve, it may be possible to investigate a moe detailed model of the BRDF based on the gamma of weaving at distinct locations

within the textile. Such studies can lead to a Bi-Diectional Textue Function (BTF) o a spatially vaying BRDF epesentation fo the cloth (Adabala et al. 2003). Such appoaches cannot be eal-time and has application in offline endeing of ealistic textiles/clothes fo digital poduction athe than fo design whee the eal-time visualization is moe useful. One of the impotant featues of cloth that has not been captued is the pesence of fibes on the suface of the cloth. We ae investigating methods fo ovecoming this limitation. ACKNOWLEDGEMENTS The authos ae gateful to Chistiane Luible fo poviding the model of the clothes used in the Figues 5 to 7. Pat of this wok has been suppoted by the Euopean poject MELIES IST-2000-28700. REFERENCES Adabala N, Magnenat-Thalmann N, Fei G, Visualization of Woven Cloth, to appea in Poceedings of the Euogaphics Symposium on Rendeing 2003 Ashikhmin M, Pemoze S, Shiley P (2000) A Micofacet Based BRDF Geneato. In: Poceedings of SIGGRAPH 2000, pp 65-74. Baaff D and Witkin A (1998) Lage steps in cloth simulation. In: Poceedings of SIGGRAPH 1998, pp 43--54. Clapp TG, Peng H, (1990) "Buckling of Woven Fabics", Textile Reseach Jounal, 60, pp 228-234 & 285-292. Collie JR, Collie BJ, O Toole G, Sagand SM, (1991) "Dape Pediction by means of Finite-Element Analysis", Jounal of the Textile Institute, 82 (1), pp 96-107. Codie F and Magnenat-Thalmann N (2002) Real time animation of desses vitual human. In EUROGRAPHICS 2002, Compute Gaphics Foum, Blackwell Publishing, vol. 21, 327 336. Daubet K, Lensch HPA, Heindich W, Seidel H-P (2001) Efficient Cloth Modelling and Rendeing, In: Euogaphics Wokshop on Rendeing 2001, pp 63-70. Gan L, et al, (1995) "A Study of Fabic Defomation using Non- Linea Finite Elements", Textile Reseach Jounal, 65(11), pp 660-668. Gölle, E., Rau, R., And Stasse, W. (1995). Modelling and visualization of knitwea. In IEEE Tansactions on Visualization and Compute Gaphics, 302 310. Gölle, E., Rau, R., And Stasse, W. (1996). Modelling textile as thee dimensional textue. In Rendeing Techniques 1996: Poc. 7th Euogaphics Wokshop on Rendeing, 205 214. Heidich W, Daubet K, Kautz J and Seidel H-P (2000) Illuminating mico geomety based on pecomputed visibility. In: Poceedings of SIGGRAPH 2000, pp.455-464. Kang TJ, Yu WR,(1995)"Dape Simulation of Woven Fabic Using the Finite-Element Method", Jounal of the Textile Institute, 86(4), pp 635-648. Kautz J, McCool M (1999) Inteactive Rendeing with Abitay BRDFs using Sepaable Appoximations, In: Euogaphics Wokshop on Rendeing 1999, pp 281-292. Kawabata S, "The Standadization and Analysis of Hand Evaluation", Hand Eval. and Stand. Committee of the Textile Machiney Society of Japan, Osaka, 1975. Meissne M and Ebehadt B (1998) The at of knitted fabics: Realistic and physically based modelling of knitted fabics. Compute Gaphics Foum, vol 17, no 3, pp 355-362. Nielsen R, Keates R, Sinkle R, Sally Beckenidge, Dana Catwight, Jane Eisenstein, Mak Kloosteman, Bjon Myhe. (1997) Weaving Infomation File Vesion 1.1. http://www.mhsoft.com/wif/wif.html. Sloan P-P, Cohen MF (2000) Inteactive Hoizon Mapping, In: Euogaphics Wokshop on Rendeing 2000 pp281-286. Volino P and Magnenat-Thalmann N (2000) Implementing fast Cloth Simulation with Collision Response. In: Compute Gaphics Intenational 2000, June 2000, pp257-268. Westin S, Avo JR, Toance KE (1992) Pedicting Reflectance Functions fom Complex Sufaces. In: Poceedings of SIGGRAPH 1992, pp 255-264. Xu Y, Chen Y, Lin S, Zhong H, Wu E, Guo B and Shum H (2001) Photoealistic Rendeing of Knitwea Using the Lumislice. In: Poceedings of SIGGRAPH 2001, pp 391-398. Yasuda T, Yokoi S, Toiwaki J, Inagaki K (1992) A Shading Model fo Cloth Objects. IEEE Compute Gaphics and Applications, vol 12, no 6, pp 15-24. Zhong H, Xu Y, Guo B and Shum H (2000) Realistic and Efficient Rendeing of Fee-Fom Knitwea, Jounal of Visualization and Compute Animation, Special Issue on Cloth Simulation, 2000 pp13-22. BIOGRAPHY NEEHARIKA ADABALA obtained he Ph.D. fom Indian Institute of Science, Bangaloe in 2000. She woked at Philips Reseach, Bangaloe, befoe joining MIRALab - Univesity of Geneva as a post-doctoal eseach assistant. He eseach at MIRALab focuses on ealistic endeing of woven clothes. NADIA MAGNENAT-THALMANN has pioneeed eseach into vitual humans ove the last 20 yeas. She studied at the Univesity of Geneva and obtained seveal degees including Psychology, Biology, Chemisty, and a PhD in Quantum Physics at the Univesity of Geneva in 1977. Fom 1977 to 1989, she was a Pofesso at the Univesity of Monteal in Canada. In 1989, she founded MIRALab, an intedisciplinay ceative eseach laboatoy at the Univesity of Geneva. She has published moe than 200 papes, is edito-in-chief of the Visual Compute and the Jounal of Visualization and Compute Animation jounal. She has eceived seveal awads and ecently, she has been nominated at the Swiss Academy of Technical Sciences. GUANGZHENG FEI obtained his Msc.degee fom Hefei Univesity of Technology in 1997, and obtained his Ph.D degee fom Institute of Softwae, Chinese Academy of Sciences in 2001. Afte doing a shot time eseach in Micosoft Reseach China, he woked in MIRALab, Univesity of Geneva as a postdoc fom 2001 to 2002 befoe moving to Animation School, Beijing Boadcasting Institute.