List of a bunch of rendering whitepapers I've found handy over the years.
NOTE: Not all of these have links I can distribute, but they can be found. They're usually just behind registration pages and such.
NOTE-2: I'll link to what I can later, I want to get the proper source and these have just accumulated in my dropbox folder.
- Real Shading in Unreal Engine 4 - Bryan Karis
- Aggregate G-Buffer Anti-Aliasing in Unreal Engine 4 - Louis Bavoil, Cyril Crassin
- genBRDF: Discovering New Analytic BRDFs with Genetic Programming - Adam Brady, Jason Lawrence, Pieter Peers, Westley Weimer
- A Non-Parametric Factor Microfacet Model for Isotropic BRDFs - Mahdi Bagher, John Snyder, Derek Nowrouzezahrai1
- VPL‐based Real‐Time GI Algorithm Light Propagation Volumes - Xin Wang
- Fast, Flexible, Physically-Based Volumetric Light Scattering - Nathan Hoobler
- Temporal Reprojection Anti-Aliasing in INSIDE - Jon Fuglsang Pedersen
- Artist Friendly Metallic Fresnel - Ole Gulbrandsen
- PBR Diffuse Lighting for GGX+Smith Microsurface - Earl Hammon, Jr
- Light Propagation Volumes in CryEngine 3 - Anton Kaplanyan
- Real-Time Polygonal-Light Shading with Linearly Transformed Cosines - Eric Heitz, Jonathan Dupuy, Stephen Hill, David Neubelt
- Deep G-Buffers for Stable Global Illumination Approximation - M. Mara, M. McGuire, D. Nowrouzezahrai, and D. Luebke
- Bump Mapping Unparametrized Surfaces on the GPU - Morten S. Mikkelson
- Global Illumination in Tom Clancy's The Division - Nikolay Stefanov
- Neural Network Ambient Occlusion - Daniel Holden, Jun Saito, Taku Komura
- Generalization of Lambert's Reflectance Model - Michael Oren, Shree K. Nayar
- Real-time Global Illumination by Precomputed Local Reconstruction from Sparse Radiance Probes - Ari Silvennoinen, Jaakko Lehtinen
- Rendering Worlds with Two Triangles with Raytracing on the GPU in 4096 Bytes - Iñigo Quilez (the demoscene even shows off in whitepapers).
- Physically-Based Shading at Disney - Brent Burley
- Spherical Illuminance Composition for Real-Time Indirect Illumination - David Kuri
- An Image Synthesizer - Ken Perlin (c'mon, gotta have this in here).
- Recursive Wang Tiles for Real-Time Blue Noise - Johannes Kopf, Daniel Cohen-Or, Oliver Deussen, Dani Lischinski
- Interactive Sketching of Urban Procedural Models - Gen Nishida, Ignacio Garcia-Dorado, Daniel G. Aliaga, Bedrich Benes, Adrien Bousseau
- Time-varying Weathering in Texture Space - Rachele Bellini, Yanir Kleiman, Daniel Cohen-Or