基于高度梯度图的微结构表面阴影绘制方法

Shadow Rendering for Meso-structure Surface Based on Height Gradient Map

针对带有微结构表面的几何模型建模困难、模型复杂度高,导致现有阴影绘制算法效率差的问题,提出一种基于高度梯度图的阴影实时绘制方法.为实现实时渲染,首先给出一种微结构描述模型,通过将微结构高度场映射到低精度模型表面来描述复杂微结构模型;然后定义微结构高度梯度图,并据此构建可见点的局部最高点集合.在阴影绘制阶段,通过实时计算梯度空间局部最高点集合遮挡来生成细节阴影.整个阴影绘制算法在图像空间完成,较好地利用了延迟着色的思想和GPU并行计算的特点,可呈现可变形物体在动态场景中的自阴影效果.

It is challenging to model the geometry of the objects with meso-structure surfaces,which have complex model structures and lead to poor performance in shadow rendering.This paper presents a real-time shadow rendering method based on height gradient map.To achieve the real-time rendering,we propose a meso-structure description model,which maps the meso-structure height field to the low-resolution model using textures.We also introduce a meso-structure height gradient map（MHGM） to create local apex sets of visible points.In the shadow rendering stage,the detailed shadow is generated by computing the occlusion of gradient-space local apex sets in real time.Our algorithm runs entirely in image space,and uses deferred shading and graphics pipeline to show the self-shadowing effect of deformable objects in dynamic scenes.