03.2 - Why Wrapping Sound Around a Sphere Changed Real-Time Rendering, but Lumen BARELY uses it скачать в хорошем качестве

03.2 - Why Wrapping Sound Around a Sphere Changed Real-Time Rendering, but Lumen BARELY uses it

Consider supporting me with $1 at https://ko-fi.com/markitekta How do you represent an infinite sky of lighting... with just 9 numbers? In this fifth episode of the Real-Time Global Illumination series, we continue our deep dive into lighting approximation by exploring Spherical Harmonics (SH) — one of the most influential techniques in the history of real-time rendering. From quantum mechanics to pixel shading, SH lets us project complex lighting onto simple mathematical functions, compressing diffuse global illumination into something fast, stable, and surprisingly elegant. 🧩 In this video, we show how Spherical Harmonics helped bridge the gap between physically based realism and real-time performance. 📚 In this episode: What are spherical harmonics, and where do they come from? How do we project lighting environments into SH? Why 9 coefficients are enough for diffuse lighting What is the dot product trick — and how does it simplify shading? What causes ringing and why sharp shadows break SH How SH powered precomputed radiance transfer, PRT, and early dynamic lighting Where Unreal Engine still uses SH — and why it isn’t enough for Lumen Whether you’ve seen SH in Unity’s light probes, Unreal’s sky lighting, or just heard the term in computer graphics circles — this episode will finally make sense of what they are and how they work. 🎬 This is part two of a three-part arc: Irradiance Caching & Probes – storing light efficiently Spherical Harmonics – compressing light with math Radiance Caching – making lighting dynamic, view-dependent, and fast ⏱ Timestamps 0:00 Intro 3:35 From 1D Signals to 2D Probes 5:20 SH and Light Probe Connection 7:49 Math Explanation 9:08 Visual Example 11:41 SH Advantages 13:13 SH Light Leak and AO 15:05 SH Ringing 16:14 Reflection Probes Problems 17:24 SH in Lumen 18:01 Outro 📚 Additional Resources 1. Green, R., 2003, March. Spherical harmonic lighting: The gritty details. In Archives of the game developers conference (Vol. 56, p. 4). 2. Sloan, P.P., 2008, February. Stupid spherical harmonics (sh) tricks. In Game developers conference (Vol. 9, p. 42). 3. Ramamoorthi, R. and Hanrahan, P., 2001, August. An efficient representation for irradiance environment maps. In Proceedings of the 28th annual conference on Computer graphics and interactive techniques (pp. 497-500). 4. 3Blue1Brown - But what is the Fourier Transform? A visual introduction.    • But what is the Fourier Transform?  A visu...   5. QuantumVisions - Spherical Harmonics (U2-05-05)    • Spherical Harmonics (U2-05-05)   6. Greger, G., Shirley, P., Hubbard, P.M. and Greenberg, D.P., 1998. The irradiance volume. IEEE Computer Graphics and Applications, 18(2), pp.32-43. 7. Sloan, P.P., Kautz, J. and Snyder, J., 2023. Precomputed radiance transfer for real-time rendering in dynamic, low-frequency lighting environments. In Seminal Graphics Papers: Pushing the Boundaries, Volume 2 (pp. 339-348). 8. Interplay of Light - Notes on occlusion and directionality in image based lighting. https://interplayoflight.wordpress.co... 9. Sloan, P.P., 2017. Deringing spherical harmonics. In SIGGRAPH Asia 2017 Technical Briefs (pp. 1-4). 10. SIGGRAPH 2012 – Local Image-based Lighting with Parallax-corrected Cubemaps 11. SIGGRAPH Advances in Real-Time Global Illumination - Radiance Caching for Real-Time Global Illumination    • Radiance Caching for Real-Time Global Illu...   👍 Like what you see? 📩 Leave a comment — I read and respond to almost all of them. 🔔 Subscribe so you don’t miss the next step in our Lumen breakdown. 🎥 Up next: Radiance Caching – How Lumen Stores View-Dependent Lighting Link to the full GI playlist    • The Road to Real Time Global Illumination   #Lumen #SphericalHarmonics #GlobalIllumination #UnrealEngine #GameDev #ComputerGraphics #Rendering #Lighting #RealTimeRendering #MARKitekta