https://congyuxiaoyoudao.github.io/tags/brdf/ Recent content in BRDF on The Only Problem's Blog Hugo -- 0.157.0 en-us Sat, 14 Jun 2025 00:00:00 +0000 https://congyuxiaoyoudao.github.io/posts/assignments/games202-homework-4/ Sat, 14 Jun 2025 00:00:00 +0000 https://congyuxiaoyoudao.github.io/posts/assignments/games202-homework-4/ <blockquote> <p>好久不见！最近在忙别的工作，这几天难得有时间，赶紧把 202 系列作业做个收尾ε٩(๑&gt; ₃ &lt;)۶з！</p> </blockquote> <hr> <h2 id="0x00-to-begin-with">0x00 To begin with</h2> <p>这篇文章将会包含以下内容：</p> <ul> <li><input checked="" disabled="" type="checkbox"> 部分课程内容回顾</li> <li><input checked="" disabled="" type="checkbox"> GAMES202 作业 4</li> </ul> <p><strong>For reference</strong>👇：</p> <ul> <li>📺B 站视频： <a href="https://www.bilibili.com/video/BV1YK4y1T7yY/?spm_id_from=333.337.top_right_bar_window_custom_collection.content.click&amp;vd_source=b6584cebba3a7a1a34d2f60d63bdc868">GAMES202-高质量实时渲染</a> </li> <li>📦代码仓库： <a href="https://github.com/congyuxiaoyoudao/GAMES202_Homework/tree/working">congyuxiaoyoudao/GAMES202_Homework at working</a> </li> <li>📃 <a href="https://blog.selfshadow.com/publications/s2017-shading-course/imageworks/s2017_pbs_imageworks_slides_v2.pdf">Revisiting Physically Based Shading at Imageworks</a> </li> </ul> <blockquote> <p>master 分支上是 202 全部作业汇总，working 分支用于提交代码。需要原始作业可下载 master 分支的包</p> </blockquote> <hr> <h2 id="0x01-课程回顾-recap">0x01 课程回顾 Recap</h2> <h3 id="能量守恒的-bsdf-energy-preserving-bsdfs">能量守恒的 BSDF Energy-Preserving BSDFs</h3> <p>Cook-Torrance 提出的微表面 BRDF 只考虑光线在表面经过一次弹射后出射到观察方向的能量，然而忽略了多次弹射最终出射到观察方向的能量，这就造成了能量损失。尤其是当材质的 roughness 较高时，G 项减小，多次弹射的比例增加，能量损失越严重。</p> <p><img alt="Missing Energy of Microfacet BRDF, Revisiting Physically Based Shading at Imageworks, SIGGRAPH 2017" loading="lazy" src="https://raw.gitmirror.com/congyuxiaoyoudao/Picgo-ImageBed/main/Assignments/Assignment%207.GAMES202HW4/202506151740381.png#center"></p> <p>2017 年 Kulla 和 Conty 受到 Disney Principle BRDF 的启发，提出了一种改进的方法，即通过引入一个能量补偿项，将多次弹射出射到观察方向的能量补充回来，就能近似地保持能量守恒。</p>