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update readme
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‎README.md‎

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@@ -33,7 +33,8 @@ This works fine when we can implicitly define intersecting method for each geome
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intersection with implicit geometries to calculating it with all triangles!
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This gives an extremely low performance when model with many faces is loaded:
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| < 200 faces (~60 fps) | ~6000 faces (< 10 fps) |
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| < 200 faces (~60 fps) | ~6000 faces (< 10 fps) |
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| -------------------------------- | ------------------------------- |
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| ![](results/BVH/simplescene.png) | ![](results/BVH/marioScene.png) |
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@@ -55,9 +56,10 @@ We can go even further with a stanford dragon (2,349,078 triangles)
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| ![](results/BVH/Dragon.png) |
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Visualizer:
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| Wahoo | Dragon | Mineway Castle |
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| ------------------------------- | ----------------------------- | --------------------------- |
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| 5117 triangles | 2,349,078 triangles | 6,490,766 triangles |
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| Wahoo | Dragon | Mineway Castle |
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| ------------------------ | ------------------------------ | ----------------------------- |
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| 5117 triangles | 2,349,078 triangles | 6,490,766 triangles |
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| ![](results/BVH/BVH.png) | ![](results/BVH/DragonBVH.png) | ![](results/BVH/CoverBVH.png) |
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# Disney BRDF Model
@@ -79,7 +81,7 @@ float sheenTint 0 1 .5
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float clearcoat 0 1 0
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float clearcoatGloss 0 1 1
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| JSON Input |
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| Input Format
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| ------------------------------------- |
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| ![](results/DisneyBRDF/jsonInput.png) |
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@@ -92,3 +94,42 @@ GUI allowing for dynamically changing parameters:
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A brief demo illustrates the usage:
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https://github.com/user-attachments/assets/62e0fcce-20bc-49f6-b9c6-eea6904767dc
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# Direct Lighting & Multi-Importance Sampling
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Consider the following 2 scenarios:
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1. When light is very small in size
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2. When we want to implement point light/directional light/spot light
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When light is small in size, it is less likely for a diffused BRDF to gather meaningful light contribution.
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Therefore, each time when light hit a surface, we can consider sample radiance directly from a light in the scene.
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This way of calculating radiance contribution is called direct lighting.
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The direct radiance from different sample point:
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| Direct Lighting Radiance |
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| ------------------------------- |
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| ![](results/MIS/DIRadiance.png) |
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But direct lighting behaves poor when sampling from a light with large area
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Veach Scene:
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| BSDF Lighting | Direct Lighting | MIS Lighting |
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| ---------------------------- | -------------------------- | ----------------------------- |
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| ![](results/MIS/MISBSDF.png) | ![](results/MIS/MISDI.png) | ![](results/MIS/MISVeach.png) |
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So a good practice might be to combine the two method. To ensure energy-conserving contribution, we use Power Heuristic to calculate the appropriate weight for the directional light radiance.
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Also by having an additional directional light contribution, we can acchieve a faster convergence. In order to make a correct contribution to our final color. At each bounce, multiply the sampled radiance with corresponding throughput (radiance `*` accumThroughput `*` BSDF(wo, wdirect)).
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| Accumulative Color (depth = 1) |
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| ------------------------------- |
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| ![](results/MIS/accumColor.png) |
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Some results:
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| MIS On | MIS Off |
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| -------------------------- | --------------------------- |
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| ![](results/MIS/MISOn.png) | ![](results/MIS/MISOff.png) |

‎results/MIS/DIRadiance.png‎

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‎results/MIS/MISBSDF.png‎

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‎results/MIS/accumColor.png‎

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‎results/MIS/beforeMIS.png‎

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‎scenes/MISConverge.json‎

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@@ -0,0 +1,86 @@
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{
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"Materials":
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{
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"light":
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{
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"TYPE":"Emitting",
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"RGB":[1.0, 1.0, 1.0],
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"EMITTANCE":10.0
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},
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"diffuse_white":
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{
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"TYPE":"Diffuse",
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"RGB":[0.98, 0.98, 0.98]
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},
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"diffuse_red":
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{
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"TYPE":"Diffuse",
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"RGB":[0.85, 0.35, 0.35]
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},
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"diffuse_green":
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{
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"TYPE":"Diffuse",
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"RGB":[0.35, 0.85, 0.35]
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},
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"specular_white":
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{
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"TYPE":"Specular",
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"RGB":[0.98, 0.98, 0.98],
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"METALLIC":1,
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"SUBSURFACE":0.0,
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"SPECULAR":1,
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"ROUGHNESS":0.3,
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"SPECULARTINT":0.0,
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"ANISOTROPIC":0.0,
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"SHEEN":0.0,
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"SHEENTINT":0.0,
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"CLEARCOAT":0.0,
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"CLEARCOATGLOSS":0.0
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}
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},
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"Camera":
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{
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"RES":[800,800],
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"FOVY":45.0,
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"ITERATIONS":3000,
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"DEPTH":8,
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"FILE":"cornell",
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"EYE":[0.0,5.0,10.5],
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"LOOKAT":[0.0,5.0,0.0],
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"UP":[0.0,1.0,0.0]
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},
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"Objects":
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[
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{
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"TYPE":"cube",
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"MATERIAL":"diffuse_white",
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"TRANS":[0.0,0.0,0.0],
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"ROTAT":[0.0,0.0,0.0],
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"SCALE":[5.0,0.005,5.0]
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},
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{
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"TYPE":"mesh",
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"MATERIAL":"specular_white",
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"FILENAME":"D:\\Fall2024\\CIS5650\\Project3-CUDA-Path-Tracer\\scenes\\objs\\Dragon.obj",
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"TRANS":[0.0,4.6,0.0],
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"ROTAT":[-85.0,0.0,0.0],
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"SCALE":[0.04, 0.04, 0.04]
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}
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],
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"Lights":
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[
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{
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"TYPE":"Area",
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"TRANS":[0.0,9.8,0.0],
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"ROTAT":[-90.0,0.0,0.0],
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"SCALE":[0.3,0.3,0.3],
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"MATERIAL":
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{
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"RGB":[1, 1, 1],
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"EMITTANCE":200.0,
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"ROUGHNESS":1.0
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}
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}
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]
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}

‎scenes/cornellNoSphere.json‎

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"METALLIC":1,
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"SUBSURFACE":0.0,
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"SPECULAR":1,
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"ROUGHNESS":0.0,
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"ROUGHNESS":0.3,
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"SPECULARTINT":0.0,
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"ANISOTROPIC":0.0,
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"SHEEN":0.0,
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{
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"RES":[800,800],
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"FOVY":45.0,
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"ITERATIONS":5000,
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"ITERATIONS":3000,
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"DEPTH":8,
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"FILE":"cornell",
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"EYE":[0.0,5.0,10.5],
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},
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"Objects":
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[
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{
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"TYPE":"cube",
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"MATERIAL":"light",
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"TRANS":[0.0,10.0,0.0],
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"ROTAT":[0.0,0.0,0.0],
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"SCALE":[1.5,0.15,1.5]
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},
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{
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"TYPE":"cube",
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"MATERIAL":"diffuse_white",
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"ROTAT":[-85.0,0.0,0.0],
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"SCALE":[0.04, 0.04, 0.04]
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}
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]
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],
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"Lights":
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[
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{
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"TYPE":"Area",
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"TRANS":[0.0,9.8,0.0],
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"ROTAT":[-90.0,0.0,0.0],
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"SCALE":[1,1,1],
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"MATERIAL":
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{
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"RGB":[0.79, 0.79, 0.79],
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"EMITTANCE":40.0,
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"ROUGHNESS":1.0
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}
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}
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],
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"Environment":
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{
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"FILENAME": "D:\\Fall2024\\CIS5650\\Project3-CUDA-Path-Tracer\\scenes\\hdri\\night1.hdr"
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}
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}

‎src/interactions.cu‎

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@@ -143,30 +143,24 @@ __device__ void MIS(
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//MIS
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float pdf_disney_for_direct = 0;
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float pdf_direct_for_disney = 0;
146-
glm::vec3 Li_disney_for_direct = glm::vec3(0.f);
147-
glm::vec3 Li_direct_for_disney = glm::vec3(0.f);
146+
glm::vec3 bsdf_direct = glm::vec3(0.f);
147+
bsdf_direct = Evaluate_disneyBSDF(m, wtl * wi_direct, wol, pdf_disney_for_direct, false, false);
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//Li_direct_for_disney = Evaluate_Li(ltw * wi_disney, intersect, pdf_direct_for_disney, intersection.directLightId, num_lights, envMap, dev_nodes, dev_triangles, dev_lights);
150-
Li_disney_for_direct = Evaluate_disneyBSDF(m, wtl * wi_direct, wol, pdf_disney_for_direct, false, false);
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//float weight_disney = PowerHeuristic(1, pdf_disney, 1, pdf_direct_for_disney);
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float weight_direct = PowerHeuristic(1, pdf_direct, 1, pdf_disney_for_direct);
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if (pdf_direct > 1e-6f)
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{
159-
glm::vec3 radiance = pathSegment.throughput * Li_direct * Li_disney_for_direct * AbsDot(wi_direct, normal) / pdf_direct * weight_direct;
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glm::vec3 radiance = pathSegment.throughput * Li_direct * AbsDot(wi_direct, normal) / pdf_direct * weight_direct * bsdf_direct;
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currAccum += radiance.x < 0 || radiance.y < 0 || radiance.z < 0 ? glm::vec3(0) : radiance;
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}
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//pathSegment.accumLight += Li_disney;
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//pathSegment.accumLight += bsdf_direct * AbsDot(wi_direct, normal) / pdf_disney_for_direct;
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//pathSegment.remainingBounces = 0;
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}
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pathSegment.remainingBounces--;
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glm::vec3 offset = normal * (isInternal ? 1e-3f : -(1e-3f));
169-
pathSegment.accumLight = currAccum;
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//pathSegment.accumLight = currAccum;
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wi = glm::normalize(ltw * wi_disney);
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pathSegment.throughput *= Li_disney * AbsCosTheta(wi_disney) / pdf_disney;

‎src/main.cpp‎

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@@ -48,7 +48,7 @@ int main(int argc, char** argv)
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const char* sceneFile = argv[1];
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// Load scene file
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scene = new Scene("D:\\Fall2024\\CIS5650\\Project3-CUDA-Path-Tracer\\scenes\\DisneyBRDF.json");
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scene = new Scene("D:\\Fall2024\\CIS5650\\Project3-CUDA-Path-Tracer\\scenes\\PT_veachScene.json");
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//scene->createBRDFDisplay();
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// test loading obj
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Material newMaterial(glm::vec3(15, 154, 255) / 255.f);

‎src/pathtrace.cu‎

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@@ -410,7 +410,10 @@ __global__ void shadeMaterialNaive(
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// If the material indicates that the object was a light, "light" the ray
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if (material.emittance > 0.0f) {
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pathSegment.remainingBounces = 0;
413-
pathSegment.accumLight += pathSegment.throughput * materialColor * material.emittance;
413+
glm::vec3 radiance = pathSegment.throughput * materialColor * material.emittance + pathSegment.accumLight;
414+
//float maxRadiance = glm::max(radiance.x, glm::max(radiance.y, radiance.z));
415+
//radiance *= maxRadiance > 0.97f ? 0.97f / maxRadiance : 1.0;
416+
pathSegment.accumLight = radiance;
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}
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else
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{

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