Painting with Light

Learn how to render beautiful images like Pixar and Disney using a simple algorithm called path tracing.
In this talk, we’ll trace the paths of billions of photons with Go on cheap cloud hardware.
Together, we’ll explore concurrency, the behavior of light, and the future of computer graphics.

Transcript

1. @hunterloftis Painting with Light GopherCon Iceland 2018
2. @hunterloftis make
3. @hunterloftis State of the Art
4. @hunterloftis 1940s: The Manhattan Project
5. @hunterloftis 1986: Kajiya's rendering equation
6. @hunterloftis 1995: Toy Story
7. @hunterloftis “There are more PhDs working on this film than any other in movie history.” - Steve Jobs, Pixar, 1995
8. @hunterloftis -$30,000,000
9. @hunterloftis -$30,000,000 +$364,545,516
10. @hunterloftis 2006: Monster House
11. @hunterloftis 2014: Big Hero 6
12. @hunterloftis
13. @hunterloftis 4 render farms
14. @hunterloftis 4 render farms 4,600 servers
15. @hunterloftis 4 render farms 4,600 servers 83 hrs / frame
16. @hunterloftis 2016: Deadpool
17. @hunterloftis 2016: Path-tracing only
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23. @hunterloftis Disney's Practical Guide to Path Tracing Late 2016
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41. @hunterloftis v0.0.1
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43. @hunterloftis 2 obstacles...
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48. @hunterloftis Obstacle #2 / confession:
49. @hunterloftis JavaScript!
50. @hunterloftis ...time to learn Go!
51. @hunterloftis Building a path tracer with Go
52. @hunterloftis Building a path tracer with Go In plain English
53. @hunterloftis Building a path tracer with Go In plain English ...with as little math as possible
54. @hunterloftis Building a path tracer with Go In plain English ...with as little math as possible ...and just a touch of physics.
55. @hunterloftis What is light?
56. @hunterloftis
57. @hunterloftis origin
58. @hunterloftis origin direction
59. @hunterloftis origin direction energy
60. @hunterloftis Origin + Direction + Energy
61. @hunterloftis What happens when light hits a surface?
62. @hunterloftis
63. @hunterloftis Reflection
64. @hunterloftis Reflection Refraction
65. @hunterloftis "conductors"
66. @hunterloftis "dielectrics"
67. @hunterloftis transmittance diffusion Once refracted, light is either transmitted or diffused
68. @hunterloftis All incoming light is either... 3. transmitted 1. reflected 2. diffused
69. @hunterloftis How can we simulate these three behaviors with Go? 3. transmitted 1. reflected 2. diffused
70. @hunterloftis BRDFs and BTDFs! "Bidirectional Reflectance Distribution Function" "Bidirectional Transmittance Distribution Function"
71. @hunterloftis BRDFs and BTDFs! "Bidirectional Reflectance Distribution Function" "Bidirectional Transmittance Distribution Function"
72. @hunterloftis A pure function that describes a material
73. @hunterloftis A pure function that describes a material
74. @hunterloftis A pure function that describes a material
75. @hunterloftis The physics have been done for us! Metals
 microfacet BRDF Non-metals
 microfacet + Oren-Nayar BRDFs Transparent materials
 microfacet BTDF + Beer's law ...car paint, hair, thin films, clouds, skin...
76. @hunterloftis But... that's just one possible path!
77. @hunterloftis But... that's just one possible path!
78. @hunterloftis But... that's just one possible path!
79. @hunterloftis “Monte Carlo integration”
80. @hunterloftis “Monte Carlo integration”
81. @hunterloftis “Monte Carlo integration” Sample a bunch of values randomly.
82. @hunterloftis “Monte Carlo integration” Sample a bunch of values randomly. Add them all up and average them.
83. @hunterloftis “Monte Carlo integration” Sample a bunch of values randomly. Add them all up and average them. That’s probably close to the real answer.
84. @hunterloftis Path tracing + Monte Carlo integration
85. @hunterloftis Path tracing + Monte Carlo integration
86. @hunterloftis 15x improvement over JS!
87. @hunterloftis How can we make more interesting images?
88. @hunterloftis Complex geometry
89. @hunterloftis Complex geometry
90. @hunterloftis Physically-based materials
91. @hunterloftis Physically-based materials
92. @hunterloftis Physically-based materials
93. @hunterloftis Image-based lighting
94. @hunterloftis Image-based lighting
95. @hunterloftis How can we make interesting images, faster?
96. @hunterloftis pprof.StartCPUProfile() File: pbr Type: cpu Time: May 31, 2018 at 6:54pm (GMT) Duration: 7.08s, Total samples = 17.55s (248.00%) Showing nodes accounting for 16.94s, 96.52% of 17.55s total Dropped 58 nodes (cum <= 0.09s) github com/hunterloftis/pbr/surface (*Triangle) Intersect 8.03s (45.75%) of 12.91s (73.56%) github com/hunterloftis/pbr/surface (*Box) Check 5.11s (29.12%) 4.88s github com/hunterloftis/pbr (*sampler) tracePrimary 0.67s (3.82%) of 16.56s (94.36%) github com/hunterloftis/pbr (*Scene) Intersect 0.01s (0.057%) of 14.47s (82.45%) 1.57s github com/hunterloftis/pbr (*sampler) traceIndirect 0.17s (0.97%) of 13.65s (77.78%) 13.65s runtime newobject 0 of 0.80s (4.56%) 0.39s github com/hunterloftis/pbr/material (*Sample) Bsdf 0.02s (0.11%) of 0.23s (1.31%) 0.18s github com/hunterloftis/pbr/surface (*Triangle) At 0.01s (0.057%) of 0.43s (2.45%) 0.06s github com/hunterloftis/pbr (*sampler) start func1 0 of 16.56s (94.36%) 16.56s github com/hunterloftis/pbr/surface (*Tree) Intersect 0.14s (0.8%) of 14.46s (82.39%) 14.46s github com/hunterloftis/pbr/surface (*Tree) IntersectSurfaces 1.18s (6.72%) of 14.09s (80.28%) 12.91s 12.90s 0.13s 0.05s 0.37s 0.23s 14.09s runtime systemstack 0 of 1.07s (6.10%) runtime (*mcache) nextFree func1 0 of 0.79s (4.50%) 0.79s runtime entersyscallblock_handoff 0 of 0.12s (0.68%) 0.12s runtime gcBgMarkWorker func2 0 of 0.12s (0.68%) 0.12s runtime (*mheap) allocSpanLocked 0.68s (3.87%) of 0.70s (3.99%) runtime mallocgc 0 of 0.92s (5.24%) 0.80s runtime (*mcache) nextFree 0 of 0.79s (4.50%) 0.79s runtime profilealloc 0 of 0.12s (0.68%) 0.12s runtime main 0 of 0.69s (3.93%) main main 0 of 0.69s (3.93%) 0.69s github com/hunterloftis/pbr/surface newBranch 0 of 0.63s (3.59%) github com/hunterloftis/pbr/surface median 0.01s (0.057%) of 0.33s (1.88%) 0.33s github com/hunterloftis/pbr/surface overlaps 0.06s (0.34%) of 0.30s (1.71%) 0.30s runtime growslice 0 of 0.33s (1.88%) 0.12s runtime memmove 0.18s (1.03%) 0.15s math/rand (*Rand) Float64 0.04s (0.23%) of 0.09s (0.51%) 0.05s github com/hunterloftis/pbr/material (*Sample) diffuse 0 of 0.11s (0.63%) 0.11s github com/hunterloftis/pbr/material (*Map) At 0.14s (0.8%) of 0.41s (2.34%) 0.26s 0.09s sort Float64s 0 of 0.23s (1.31%) 0.23s 0.41s sort (*Float64Slice) Less 0.14s (0.8%) 0.24s runtime mach_semaphore_signal 0.12s (0.68%) runtime stkbucket 0.11s (0.63%) sort doPivot 0.04s (0.23%) of 0.22s (1.25%) 0.14s runtime scanobject 0.06s (0.34%) of 0.09s (0.51%) runtime timerproc 0 of 0.14s (0.8%) runtime notetsleepg 0 of 0.14s (0.8%) 0.14s github com/hunterloftis/pbr/surface NewTree 0 of 0.68s (3.87%) 0.02s 0.63s github com/hunterloftis/pbr/geom Direction RandHemiCos 0.01s (0.057%) of 0.11s (0.63%) 0.02s github com/hunterloftis/pbr/geom RandDirection 0 of 0.11s (0.63%) 0.08s runtime gcBgMarkWorker 0 of 0.13s (0.74%) 0.13s runtime gcDrain 0 of 0.12s (0.68%) 0.03s 0.09s 0.02s runtime entersyscallblock 0 of 0.12s (0.68%) 0.12s runtime mProf_Malloc 0.01s (0.057%) of 0.12s (0.68%) 0.11s github com/hunterloftis/pbr (*Render) Start 0 of 0.69s (3.93%) github com/hunterloftis/pbr (*Scene) prepare 0 of 0.69s (3.93%) 0.69s 0.68s 0.11s main iterativeRender 0 of 0.69s (3.93%) 0.69s main run 0 of 0.69s (3.93%) 0.69s 0.69s 0.79s runtime (*mcache) refill 0 of 0.79s (4.50%) 0.79s runtime (*mcentral) cacheSpan 0 of 0.79s (4.50%) 0.79s runtime (*mcentral) grow 0 of 0.79s (4.50%) 0.79s runtime (*mheap) alloc 0 of 0.76s (4.33%) 0.76s runtime (*mheap) alloc func1 0 of 0.74s (4.22%) 0.74s runtime (*mheap) alloc_m 0 of 0.74s (4.22%) 0.74s 0.70s 0.12s runtime handoffp 0 of 0.12s (0.68%) 0.12s 0.12s runtime startm 0 of 0.12s (0.68%) 0.12s runtime mach_semrelease 0 of 0.12s (0.68%) 0.12s runtime notewakeup 0 of 0.12s (0.68%) runtime semawakeup 0 of 0.12s (0.68%) 0.12s 0.12s 0.12s 0.12s sort Sort 0 of 0.23s (1.31%) 0.23s sort quickSort 0 of 0.23s (1.31%) 0.23s 0.22s github com/hunterloftis/pbr/surface (*Triangle) Intersect 8.03s (45.75%) of 12.91s (73.56%) github com/hunterloftis/pbr/surface (*Box) Check 5.11s (29.12%) 4.88s runtime newobject 0 of 0.80s (4.56%) github com/hunterloftis/pbr/surface (*Tree) IntersectSurfaces 1.18s (6.72%) of 14.09s (80.28%) 12.91s 0.23s 14.09s runtime systemstack 0 of 1.07s (6.10%) runtime mallocgc 0 of 0.92s (5.24%) 0.80s runtime (*mcache) nextFree 0 of 0.79s (4.50%) 0.79s runtime profilealloc 0 of 0.12s (0.68%) 0.12s runtime growslice 0 of 0.33s (1.88%) 0.12s 0.15s math/rand (*Rand) Float64 0.04s (0.23%) of 0.09s (0.51%) 0.05s 0.26s 0.09s 31%) 0.23s 0.24s %) 5%) runtime timerproc 0 of 0.14s (0.8%) runtime notetsleepg 0 of 0.14s (0.8%) 0.14s github com/hunterloftis/pbr/geom Direction RandHemiCos 0.01s (0.057%) of 0.11s (0.63%) 0.02s github com/hunterloftis/pbr/geom RandDirection 0 of 0.11s (0.63%) 0.08s runtime gcBgMarkWorker 0 of 0.13s (0.74%) 0.13s 0.02s runtime entersyscallblock 0 of 0.12s (0.68%) 0.12s runtime mProf_Malloc 0.01s (0.057%) of 0.12s (0.68%) 0.11s 0.79s 0.12s 0.12s 1%) 23s 1%) 23s 22s
97. @hunterloftis Accelerating data structures
98. @hunterloftis Accelerating data structures
99. @hunterloftis Concurrency
100. @hunterloftis 1/4 Byte of Go trivia
101. @hunterloftis 1: Meaningless operations
102. @hunterloftis 1: Meaningless operations
103. @hunterloftis 1: Meaningless operations
104. @hunterloftis 1: Meaningless operations
105. @hunterloftis 1: Meaningless operations
106. @hunterloftis 1: Meaningless operations "Two meters tall plus a halogen light bulb."
107. @hunterloftis 1: Meaningless operations "Two meters tall plus a halogen light bulb." "Fuchsia moved to the right."
108. @hunterloftis Fix: Named types!
109. @hunterloftis Fix: Named types!
110. @hunterloftis Fix: Named types!
111. @hunterloftis 2: Hidden synchronization https://golang.org/src/math/rand/rand.go
112. @hunterloftis 2: Hidden synchronization https://golang.org/src/math/rand/rand.go
113. @hunterloftis 2: Hidden synchronization https://golang.org/src/math/rand/rand.go
114. @hunterloftis 2: Hidden synchronization https://golang.org/src/math/rand/rand.go
115. @hunterloftis Fix: Dependency injection!
116. @hunterloftis The Future
117. @hunterloftis 2018
118. @hunterloftis 2018
119. @hunterloftis 2018
120. @hunterloftis 2018
121. @hunterloftis An exciting, emerging field Research that hasn't been implemented yet "Embarrassingly parallel" algorithm Dominated by C++
122. @hunterloftis I would love your help! Roadmap distributed concurrency glTF files, normal/displacement maps motion, participating media, subsurface scattering performance, better idiomatic Go, GPU support beautiful example scenes!
123. @hunterloftis How's the doing?
124. @hunterloftis Thank you! https://github.com/hunterloftis/pbr https://www.disneyanimation.com/technology/innovations/hyperion http://www.cse.chalmers.se/edu/year/2013/course/TDA361/Pathtracing.pdf http://blog.selfshadow.com/publications/s2015-shading-course/hoffman/s2015_pbs_physics_math_slides.pdf https://www.cs.cmu.edu/afs/cs/academic/class/15462-f09/www/lec/lec8.pdf https://www.atomicheritage.org/history/computing-and-manhattan-project https://graphics.pixar.com/library/PathTracedMovies/paper.pdf https://www.wired.com/1995/12/toy-story/ Hunter@Heroku.com