基于动态纹理火焰生成.pdf

摘要
火焰模拟是自然景物模拟的一个重要研究内容,现有的火焰模拟算法分为两大
类,直接数字合成与视觉效果建模。其中基于视觉效果模拟包括火焰模型、湍流理
论、粒子系统等。本文根据最近几年才迅速发展的动态纹理技术提出一个基于纹理
合成火焰的方法。一般的纹理合成算法大都是在静止物体表面包括在二维平面上
处理,也有个别的可以合成各向同性的动态纹理序列,如远处观看的水面等。
计算机方法合成火焰需要处理火焰轮廓和火焰轮廓内部的纹理。本文用两种方
法再现火焰轮廓,一个是用噪声函数作速度场的火焰轮廓线构造算法,通过轮廓线
骨架粒子在速度场中运动展现火焰燃烧时的动态信息。另一个是直接采用真实火焰
序列中提取出来的火焰轮廓线。
利用动态纹理合成火焰需要解决以下几个问题在火焰动画序列中保证火焰
纹理动态连续向上运动;火焰中心部位与火焰边缘区域不同纹理之间的自然过渡。
我们使用动态纹理技术对真实的火焰视频进行学习,并生成无限长不重复的火
焰图像序列。使用这种方法生成的火焰具有很强的真实感和一定的可编辑性。适合
在场景较为开阔,对火焰的实时性和逼真度要求较高的虚拟场景中使用。大规模火
焰蔓延过程通过火焰轮廓线动态修改和交叉纹理线性过渡来实现,最后我们给出如
何在三维空间中再现大面积火焰的方法。

关键词:火焰模拟火焰轮廓线粒子系统纹理绘制纹理合成
火焰蔓延动态纹理

I
Abstract
Computer simulation of fire is an important research area. Existing fire simulation
techniques can be classified into two categories: direct numerical simulation and visual
modeling. Base on dynamic texture technique developed in recent years, we propose a
new approach for the synthesis of fire.
Computer simulation of fire needs to solve two problems: determination of fire contour
and fire texture inside the contour. In this thesis we deal with fire contour by use of noise
function or abstracting the contour from real fire series.
To synthesize fire we need to following problems: 1. maintaining the movement
continuity of varying fire texture in the synthesized fire series; 2. natural transition
between textures from the central part to the boundary part of the fire.
We use dynamic texture technology learned from real flames video, and the flames
generated images unlimited long series of non-repetition. Generated by the use of such
methods is highly flame and some may warrant editorial. And it maybe more suitable to
use in open scenes, such as the real-time nature of the flame for higher degrees and
realistic virtual scenes. The texture on the overlap area between neighboring fire bodies is
dealt with by use of linear interpolation of textures between crossing areas of the two fire
bodies. Finally we show how