Notes of Substance PBR(physically based rendering) shader

(a) UV shifting with relief mapping

• linear and binary search to calculate ray intersection with height_map

(b) 2 point light

• Diffuse direct lighting : Lambert
• Specular direct lighting : F(Schlick with Spherical Gaussian approximation), G(Schlick with Smith-like choise of k. [UE4]), D(GGX [UE4])

(c) 1 Image based lighting

• Diffuse indirect lighting : Irradiance SH from EnvMap
• Specular indirect lighting : Importance sampling of EnvMap based on GGX with QMC using Hammersley 2D samples [UE4] with "Horizon Occlusion for Normal Mapped Reflections"

(d) Emission

• emission_texture * emission_intensity

Reference

• "Real Shading in Unreal Engine 4"
• "Horizon Occlusion for Normal Mapped Reflections"

The difference between relief mapping and Parallax Occlusion Mapping

Difference

• Relief Mapping : linear and binary search, hard shadow
• Parallax Occlusion Mapping : linear search with surface-ray intersection, soft shadow

Reference

• • "Practical Parallax Occlusion Mapping For Highly Detailed Surface Rendering. SIGGRAPH 2006"

Notes of cascaded shadow maps

• DirectX SDK : CascadedShadowMaps11
• https://msdn.microsoft.com/en-us/library/windows/desktop/ee416307(v=vs.85).aspx
• https://msdn.microsoft.com/en-us/library/windows/desktop/ee416324(v=vs.85).aspx
• http://developer.download.nvidia.com/SDK/10.5/opengl/src/cascaded_shadow_maps/doc/cascaded_shadow_maps.pdf
• Light Perspective Shadow Maps : http://www.cg.tuwien.ac.at/research/vr/lispsm/shadows_egsr2004_revised.pdf
• Perspective Shadow Maps : http://http.developer.nvidia.com/GPUGems/gpugems_ch14.html
• Variance Shadow Maps : http://developer.download.nvidia.com/SDK/10/direct3d/Source/VarianceShadowMapping/Doc/VarianceShadowMapping.pdf