杨 丹,汤晓安

摘 要:针对港口三维监控系统中云绘制的特点,分析云绘制的逼真度和实时性需求,研究相应的云绘制方法,提出一种基于噪声纹理的云层绘制方法。该方法采用基于纹理构造云模型,降低了所需绘制的几何数据;采用设置纹理重复模式,实时更改纹理矩阵,实现云层运动的效果,采用多纹理技术将两张噪声纹理成一定角度叠加,实现云自身形态的连续变化。通过该方法绘制了港口三维监控系统云层,具有较强的三维虚拟现实的真实感。实验结果表明,该方法可显著提高云绘制效率,显示效果令人信服。

关键词:三维监控系统;云绘制;噪声纹理;多纹理

中图分类号:TP311.13文献标识码:A

文章编号:1004-373X(2009)20-040-02

Method of Plotting Clouds Based on Noise-Texture Operator

YANG Dan,TANG Xiaoan

(College of Electronic Science and Engineering,National University of Defense Technology,Changsha,410073,China)

Abstract:Aiming at the features of plotting clouds in the port three-dimensional monitoring system,the fidelity and timeliness requirements of plotting clouds are analysed,the method of corresponding plotting clouds is researched,a method of plotting clouds based on a noise-texture operator is put forward.This method uses cloud model based on texture and reduces the geometry data ,sets texture repeat mode,changes the texture of real-time matrix and realizes the cloud layer movement effect.Using the multi-texture technology superimposes two noise textures according to a certain point of view and realizes the cloud continual change.In this way,plot clouds of the port three-dimensional monitoring system and the realistic of three-dimensional virtual reality is enhanced.Experiments demonstrate that the method could improve efficiency of plotting clouds,so the effect of display is convinced.

Keywords:three-dimensional monitoring system;plotting clouds;noise-texture;multi-texture

云的绘制在港口三维监控系统中,不属于最核心的显示内容,但是对于增强三维虚拟现实的沉浸感有非常大的作用。因此必须找到显示效果既能令人信服,同时绘制效率又高的云绘制方法。

在此面向刚空三维监控系统中云的特点,针对现有云绘制方法的不足,提出了构造Perline噪声纹理,并采用简便合理的纹理矩阵变换方法,实现了云层的绘制,其具有一定的应用参考价值。

1 经典的云层建模

1.1 云层建模的四种常用方法

体过程建模方法(Volumetrie Proceduml Modeling)是一种过程建模方法。体过程也称为超纹理(Hypertextures)、体密集度函数(Volume Density Functions)或者模糊滴状斑点(Fuzzy Blobbies),它利用一定算法对三角体对象和自然现象进行定义和动画[1]。1985年Geoffrey Y.Gardner提出的云模型由一个天空平面、椭球体和数学纹理函数三部分组成。……