OpenCascade Ray Tracing Rendering

OpenCascade Ray Tracing Rendering

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摘要Abstract:OpenCascade6.7.0中引入了光线跟踪算法的实现。使用光线跟踪算法可实现高质量的渲染效果,且可以使用GPU提升渲染效率。 

关键字Key Words:OpenCascade, Ray Tracing 

  

参考链接:Ray tracing as alternative rendering method for OCCT visualization component 

http://dev.opencascade.org/index.php?q=node/898

 

OpenCascade 6.7.0对显示部分做了些重大改进,其中突破性的改变是使用OpenCL实现了光线跟踪算法。作为库TKOpenGl的一部分,光线跟踪算法与标准的显示模块完全集成。从此,光线跟踪也可以作为显示的一种方法。与其他第三方库的光线跟踪库的区别是,内置的光线跟踪算法确保了实时渲染时的性能,性能与OpenGL的性能相近,在有大量模型时性能比OpenGL的还要好。 

光线跟踪功能如下: 

l High-quality shading by interpolating normal across the triangle pixels and using advanced illumination model (Phong shading); 

l Depth-correct order-independent transparency for any number of overlapped objects; 

l Sharp shadows from isotropic point and directional lights without any approximation – greatly improve visual appearance; 

l Specular reflections and environment mapping – for high-quality rendering of metallic surfaces; 

l Low-cost adaptive anti-aliasing allows to improve image quality by removing jagged edges from the image; 

l Based on cross-platform OpenCL framework – runs on GPUs of major vendors (NVIDIA and AMD/ATI); 

l Makes the most of the mid-/top-range GPUs but also runs successfully on low-end GPUs that support OpenCL。 

只要OpenCascade编译时启用OpenCL支持,光线跟踪的使用是相当简单,只需要调用函数V3d_View::SetRaytracingMode()就可以把3D view切换成光线跟踪渲染啦。参考V3d_View和文档或者Draw Test Harness的vraytrace和vsetraytracemode命令实现的源程序去详细了解如何设置光线跟踪的一些选项。 

最简单的测试光线跟踪的方式是在Draw Test Harness中输入如下命令:

Draw[ 2 ] >  source samples / tcl / bottle.tcl 

生成效果如下图所示: 

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Figure 1.1 Render bottle and text with ray tracing 

image 

Figure Render my email with Ray tracing

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Figure 1.2 Render pipe and equipment models with ray tracing 

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Figure 1.3 Render pipe and equipment models with ray tracing 

从上图可知,使用光线跟踪效果很不错,可以看到镜面效果,很Cool!

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