__  ___      ___      ________   _______ .__   __.   
 |  |/  /     /   \    |       /  |   ____||  \ |  | 
 |  '  /     /  ^  \   `---/  /   |  |__   |   \|  | 
 |    <     /  /_\  \     /  /    |   __|  |  . `  | 
 |  .  \   /  _____  \   /  /----.|  |____ |  |\   | 
 |__|\__\ /__/     \__\ /________||_______||__| \__| 
====================================================================
 nano-kazen: Physically Based Renderer                              
 Version Alpha 0.1.0                                            
 Copyright (C) 2022 ZhongLingXiao && Joey Chen. All rights reserved.                          
====================================================================

💡 nano-kazen

Experimental cpu based path tracer

kazen-con 2 : katastrophe

Figure 1: 1920x1080 | 16384 spp | 1.1 h

Core Feature

1. New samplers
   • stratified
   • correlated
   • pmj02-bn
2. Geometric shadow terminator : remove the shadow-line artifact cause by geometry
3. Fire fly reduction: increase roughness per bounce
4. Configurable ray bias for reduce ray intersection computations error
5. Light primary visibility : toggle light visibility

See the full kazen-2022-q2 report

Reference

[1] Stochastic Sampling in Computer Graphics ROBERT L. COOK. 1986

[2] Correlated Multi-Jittered Sampling Andrew Kensler. 2013

[3] Andrew Kensler's permute() Andrew Helmer. 2021

[4] Progressive Multi-Jittered Sample Sequences Per Christensen, Andrew Kensler and Charlie Kilpatrick. 2015

[5] Physically Based Rendering v4 Matt Pharr, Wenzel Jakob and Greg Humphreys. 2023

[6] Hacking the Shadow Terminator Johannes Hanika. 2021

[7] Accumulate a roughness bias based on roughness of hitting surface Yuriy O'Donnell. 2019

[8] Ray Tracing Denoisinge Alain Galvan. 2020

kazen-con 1 : kiss pbr shading model

Figure 2: 3840x2160 | 10000 spp | 3.4 h

Core Feature

1. Monte Carlo unbiased path tracing
2. multiple importance sample
3. Material ：kazen initial standard surface ( kiss )
   • diffuse ：Disney diffuse with Retro-Reflective
   • specular ：GGX-Smith BRDF with VNDF
   • clearcoat ：GGX-Smith BRDF with VNDF
   • sheen ：Disney sheen
4. Textures and simple textures ops ( nested blend, ramp color, scale uv )
5. OIIO texture system
6. Normal mapping
7. Camera : Perspective | Thin Lens
8. Light : mesh light, basic environment ( Blinn/Newell Latitude Mapping )

See the full kazen-2022-q1 report

Reference

[1] Physically Based Shading at Disney Brent Burley. 2012

[2] Extending the Disney BRDF to a BSDF with Integrated Subsurface Scattering Brent Burley. 2015

[3] Simon Kallweit's project report Simon Kallweit. 2015

[4] Microfacet Models for Refraction through Rough Surfaces Bruce Walter. 2007

[5] Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs Eric Heitz. 2014

[6] Sampling the GGX Distribution of Visible Normals Eric Heitz. 2018

[7] ROBUST MONTE CARLO METHODS FOR LIGHT TRANSPORT SIMULATION Eric Veach. 1997

[8] Physically Based Rendering: from theory to implementation Matt Pharr, Wenzel Jakob and Greg Humphreys. 2016

[9] Mitsuba 2: Physically Based Renderer Wenzel Jakob

[10] Embree 3: High Performance Ray Tracing Intel

[11] OpenImageIO Larry Gritz

[12] Greyscalegorilla: modern surface material collection Greyscalegorilla. 2021