Physically-Based Real-Time Diffraction Using Spherical Harmonics
Physically-Based Real-Time Diffraction Using Spherical Harmonics
复制标题
使用球谐函数进行基于物理的实时衍射
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
E. Agu
中科院分区：
文献类型：
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作者：
Clifford Lindsay;E. Agu
衍射、干涉、色散折射和散射是产生彩虹色的四种波长相关机制。波长相关的函数需要在可见光谱的离散波长处采样，这增加了绘制彩虹色的计算强度。此外，衍射需要仔细采样，因为它的响应函数变化频率比干涉或色散折射更高，峰值更明显。因此，绘制物理上精确的衍射以前要么使用简化的颜色曲线近似，要么仅限于离线绘制技术，如光线追踪。我们提出了一种在可编程硬件上实时绘制物理精确衍射图的技术。该技术自适应地对衍射BRDF进行采样，并将其预计算为保留反射光峰值强度的球谐基。虽然以前的衍射工作使用低动态范围的光，但我们保留了入射照明的全动态范围和整个半球入射光方向的衍射响应。我们推迟从波长表示到色调映射的RGB三元组的转换，直到显示。
Diffraction, interference, dispersive refraction and scattering are four wavelength-dependent mechanisms that produce iridescent colors. Wavelength-dependent functions need to be sampled at discrete wavelengths in the visible spectrum, which increases the computational intensity of rendering iridescence. Furthermore, diffraction requires careful sampling since its response function varies at a higher frequency variation with sharper peaks than interference or dispersive refraction. Consequently, rendering physically accurate diffraction has previously either been approximated using simplified color curves, or been limited to offline rendering techniques such as ray tracing. We propose a technique for real-time rendering of physically accurate diffraction on programmable hardware. Our technique adaptively samples the diffraction BRDF and precomputes it to Spherical Harmonic (SH) basis that preserves the peak intensity of the reflected light. While previous work on diffraction used low dynamic range lights, we preserve the full dynamic range of the incident illumination and the diffractive response over the entire hemisphere of incoming light directions. We defer conversion from a wavelength representation to a tone mapped RGB triplet until display.