Research On Key Technologies Of Dynamic Cloth Simulation

Cloth simulation is a hard technology. It is one of research focuses in the fields of computer graphics and textile engineering. In this thesis, we study some typical cloth simulation technologies and proposed a parameterized modeling scheme of the human body. The thesis apply the theories and technologies in the virtual dressing system and gain some significant achievements.First, a survey on the researches and advances of relevant technologies for cloth simulation is described. The advantage and disadvantage of cloth modeling are analyzed. Then the difficult points and research focuses in the research field is pointed out.In the thesis, the cloth is classified with different methods, and analyze the structural characteristic of various fabrics. The physical performances of fabric are defined in detail. In the thesis, the testing methods and evaluations of fabric are described.Based on the garment features, the main measurements of human body such as height of stature, width of shoulder, circumference of bosom, waist and hip etc are achieved according the relations between the garment and human body. A parameterized modeling scheme is proposed for virtual dressing system. The scheme has advantages of small data amount, simpleness, fast speed, easy implement and individuation. However, the meshes of 3D human body model with few data points are rough and have low resolving capability. Mesh quality is improved by means of Loop subdivision algorithm, which is a smoothing algorithm to improve the geometrical model of the human body model.In this research, an idea is adopted to apply the cloth properties in the accurate cloth simulation and an efficient numerical integration approach to solve cloth motion equations. We analyze the parameters and getparms method that is used to express the cloth appearance. Cloth can be seen as a mechanical system that made up with large numbers of masses, as so called Spring-Mass model. Considering the cloth properties among masses, cloth style can be represented with parameterized Spring-Mass model. In the thesis, based on the survey of numerical integration approaches, an improved embedded Runge-Kutta algorithm is proposed. Compared with the other Runge-Kutta scheme, the proposed scheme has some advantages for cloth simulation: controllable error evaluation without extra computations, excellent efficiency, good stability and satisfied precision. Experiment demonstrates that this method results in simulation efficiency improvements and is considerable practicable.Collision detection and reality are key technologies of cloth animation. Compared with rigid object, the collisions of cloth are more complex. There are two collisions in cloth animation: one is happened between cloth and the other rigid object, the other is happened between cloth and cloth itself. Different schemes are used to solve two collisions in cloth animation: bounding box hierarchy subdivision is used to detect the collision between cloth and rigid object; vector triangulated mesh surface is used to detect the collision between cloth and cloth itself. Texture mapping and physical lighting model are also described to increase the reality of cloth animation.Vectorized mesh subdivision is a key technology to complete 2D/3D transformation of garment panel. Vectorized mesh generating theory is introduced and a mesh subdivision algorithm for cloth simulation is proposed also. A simple Spring-Mass model including only structural spring and bending spring is implemented in our virtual dressing system. The forces act on the mass is analyzed and three different seaming models are presented.All of these analyses are supported by experiments. A virtual dressing system is developed. The functional modules and system structure are introduced. Compared with other virtual clothing system, our system avoids vast collisions caused by dynamical iterations. Some satisfied achievementsis obtained. Some tentative for future work are proposed.