双光源环境下非真实感绘制色调获取方法研究

Method of Catching NPR Hue in Double Light Source Condition

非真实感绘制场景中客体明暗色调的合理性和协调性直接影响到最后生成画面的效果。对双光源环境下非真实感绘制场景中客体色调的获取方法进行研究,提出一种双光源下基于"小球法"的色调信息提取方法,该方法假设场景中的客体表面均匀覆盖了一层大小相同的小球,相邻的两个小球间保持近似相切状态,通过计算每一个小球在双光源状态下被其它小球遮挡的程度来确定该小球中心位置的明暗信息,以及每一个小球在双光源环境下所在位置的近似镜面反射光亮度。在绘制阶段,可利用这些色调信息控制在相应位置绘制"笔触"的色调,从而保证所生成的非真实感画面场景整体色调的合理性。该方法可应用于双光源下各种非真实感绘制明暗信息的获取,并且具有结构简单、计算速度快和可方便实现对场景中局部信息的调整等特点。实验结果验证了提出的方法的有效性。

In NPR,a reasonable light and shade and coordination directly affect the effect of the last created menu.This paper discussed the methods of catching the tone of the object in Non-photorealistic rendering scene in double light source condition,and presented a method which can obtain hue information of the scene and objects based on small ball,this method supposes the surface of objects in scene is symmetrically covered with a layer of the same size balls,and two adjacent balls maintain a state of approximate tangent,by computing the ball＇s sheltered degree by other balls in double light source condition and the approximate mirror reflection information to confirm the hue information of the small ball in it＇s position.These hue informations can be used to control brushstroke＇s hue at the corresponding position in the process of painting,thereby ensures the rationality of the whole hue in the last created menu.This method can be applied to a variety of double light source non-photorealistic rendering for obtaining light and shade information,and has simple structure,fast computation speed and facilitate the realization the adjustment of local information in scene.Simulation results show it is effective.