基于PTM模型文物纹理映射算法

针对三维重建物体纹理不真实与不精确问题,提出了基于PTM(Polynomial Texture Maps)模型的文物纹理映射算法,该算法利用了多项式颜色依赖性的特质,采取表征颜色与亮度依赖关系的双二次多项式系数进行存储纹素数据,从而实现在变化的光照条件下重建物体的表面纹理。此外针对原PTM模型中存在的原始采集图像漫反射异常、亮度信息分布不均匀、重建拟合系数不精确,导致的重建图像纹理模糊、存在重影、物体细节纹理缺失等问题,提出了改进多项式的基函数和优化拟合系数的PTM算法以及PTM图像采集设备的优化方法,最后经实验验证,提出的算法使得重建物体纹理的真实性与精确度均得到了有效提高。

基于多项式纹理的Lengyel毛发实时绘制

针对普通绘制毛发光照效果方法存在的实时性较差的问题,提出一种基于多项式纹理的Lengyel毛发实时绘制方法,将多项式纹理融入Lengyel绘制毛发方法中。在预处理阶段,对毛发模型进行采样,并计算纹元的多项式纹理系数,利用该系数计算不同光照下纹元的亮度信息,通过所得亮度信息确定当前光照下纹元的颜色值,并由内到外对毛发网格层进行融合绘制。实验结果表明,该方法可以满足中等规模物体的实时绘制需求。

Designing Bézier surfaces minimizing the L^2-norm of the Gaussian curvature

In freeform surface modelling, developable surfaces have much application value. But, in 3D space, there is not always a regular developable surface which interpolates the given boundary of an arbitrary piecewise smooth closed curve. In this paper, tensor product Bézier surfaces interpolating the closed curves are determined and the resulting surface is a minimum of the functional defined by the L2-integral norm of the Gaussian curvature. The Gaussian curvature of the surfaces is minimized by the method of solving nonlinear optimization problems. An improved approach trust-region form method is proposed. A simple application example is also given.