Fast physical simulation of virtual clothing based on multilevel approximation strategies

One of the primary disadvantages of Internet telepresence implemented using currently available technology is the lack of 'touch and feel' available to users. This problem is particularly acute with regard to Internet retailing, since customers generally prefer to try clothing on before purchasing it; even those customers who buy items via mail order catalogues exhibit a high return rate and do so at considerable cost to the retailer. A virtual mannequin service, which uses a computer-generated representation of the consumer to 'try on' different items and combinations of virtual clothing, would provide an excellent solution to this problem. The consumer could easily see how various sizes, styles, and combinations of garments would look on their own person yet without leaving the home or office. However, until now the possibility of such a service for telepresence shopping systems has been unrealistic due to the number and complexity of calculations required for the modelling of physical clothing items. This thesis presents a full account of the FIGMENT scheme (Fast Implementation Garment Modelling environmENT) which incorporates a four-point strategy (a simplified physical model, collision volume approximation, progressive meshes and a hybrid rendering algorithm) acting at multiple levels in the modelling process to reduce the quantity and complexity of the computations involved, bringing modelling times from the realm of hours to minutes and seconds whilst maintaining an acceptable level of accuracy and fidelity in the results. The physical model permits garment models obtained by various methods to be used in simulations, incorporates alternative methods of force computation to allow a range of speed-accuracy levels, and provides a robust basis for the other aspects of the scheme. The two methods of collision volume approximation presented enable collision handling in 0(n) time rather than the 0(nlogn) time of optimised polygon-to-polygon detection methods whilst providing other advantages germane to the modelling process. The further development and employment of progressive mesh algorithms permits an additional increase in modelling rates without loss of fidelity. Finally, the use of a hybrid rendering algorithm which combines depth-buffering and depth-sorting techniques effectively masks the minor visual discrepancies introduced by the other points of the scheme and enables the use of multilayered complex garments without resorting to cloth-to-cloth collision methods (both of which would require considerable additional computation to otherwise achieve), whilst only marginally affecting modelling rates. When fully implemented, the FIGMENT scheme can reduce modelling times by a factor of 80 in typical cases. The aim of the thesis is to detail the design principles and the algorithms which together comprise the FIGMENT scheme and to demonstrate by way of example and user tests the benefits typically afforded by implementing a virtual mannequin service based on the scheme. The contribution of this thesis is therefore to present a set of novel approaches to modelling clothing which would together allow the implementation of a virtual mannequin service using the levels of hardware and software technology which presently exist in the majority of computer-equipped homes and offices, yet without hindering the usability of such a service.