Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> E. PARTICLE RENDERING <s> Detail enhances the visual richness and realism of computer-generated images. Our stochastic modelling approach, called particle systems, builds complex pictures from sets of simple, volume-filling primitives. For example, structured particle systems have been used to generate trees and a grass-covered forest floor. Particle systems can produce so much irregular, three-dimensional detail that exact shading and visible surface calculations become infeasible. We describe approximate and probabilistic algorithms for shading and the visible surface problem. Because particle systems algorithms generate richly-detailed images, it is hard to detect any deviation from an exact rendering. Recent work in stochastic modelling also enables us to model complex motions with random variation, such as a field of grass blowing in the breeze. We analyze the performance of our current algorithms to understand the costs of our stochastic modelling approach. <s> BIB001 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> E. PARTICLE RENDERING <s> Every time a tablecloth is draped over a table it will fold and pleat in unique ways. We report on a physically-based model and a simulation methodology, which when used together are able to reproduce many of the attributes of this characteristic behavior of cloth. Our model utilizes a microscopic particle representation that directly treats the mechanical constraints between the threads in woven material rather than using a macroscopic continuum approximation. The simulation technique is hybrid, employing force methods for gross movement and energy methods to enforce constraints within the material. The model is developed and demonstrated within a visualization environment that allows full interaction between the simulated material and conventional constructive-solid-geometry models. <s> BIB002
Once the parameters of all particles are calculated, the rendering algorithm starts. The general particle-rendering problem is as complicated as the rendering of objects composed of numerous common graphical primitives. The methods of rendering are likewise different from one another due to the different forms of the particles themselves BIB001 ,  , BIB002 . 1) POINT PARTICLE MAPPING In the particle system, a large number of particles are used to ensure realistic simulation but simultaneously consumes enormous time and space consumption for calculation and rendering. Therefore, the following are assumed to improve the rendering speed in the Reeves-based particle system: • All particle systems include particles that are assumed to be a point source. This avoids numerous complicated operations, such as the shadow of a single particle being no longer considered, regardless of the particle reflection on light. Particles that map to the same pixels in the image are additive, and the pixel color is simply the sum of the color values of all the particles that map to it. No hidden surface algorithms are needed to render the image due to such assumption; the particles are simply rendered in order. • The relationship between particles, such as collision and fusion, are ignored. Collision detection between particles is a very complex problem because this study focuses on the overall shape of the particles. Such detection is neither realistic nor necessary.