1 minute Path tracing Bidirectional path tracing Progressive - - PowerPoint PPT Presentation

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Sep 18, 2023 268 likes •690 views

Path tracing Bidirectional path tracing Progressive photon mapping 1 minute Path tracing Bidirectional path tracing Progressive photon mapping 1 minute Bidirectional path tracing Relative efficiency Result Progressive photon mapping

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Bidirectional path tracing Progressive photon mapping

1 minute

Path tracing

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Bidirectional path tracing Progressive photon mapping

1 minute

Path tracing

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Relative efficiency Bidirectional path tracing Progressive photon mapping Result

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Bidirectional path tracing Photon mapping

Unidirectional sampling Vertex connection Density estimation

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𝐽

𝑘 = 𝑔 𝑘 x

𝑞 x 𝐽

𝑘 = න Ω

𝑔

𝑘 x 𝑒𝜈(x)

x0 x1 x𝑙−1 x𝑙

𝑞 x = 𝑞 x0 𝑞 x1 … 𝑞 x𝑙

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x0 x1 x2 x3

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x0 x1 x2 x3

Light vertex Camera vertex

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x0 x1 x2 x3 x0 x1 x2 x3

Bidirectional path tracing Photon mapping

Light vertex Camera vertex

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Photon mapping

x0 x1 x2 x3 x0

𝑞𝑊𝐷 x = 𝑞 x0 𝑞 x0 → x1 𝑞(x3)𝑞 x3 → x2 𝑞𝑊𝑁 x =

Bidirectional path tracing

𝑞𝑊𝑁 x ≈ 𝑞 x0 𝑞 x0 → x1 𝑞 x1 → x2

∗ 𝜌𝑠2

𝑞 x3 𝑞(x3 → x2)

x3 x1 x2 𝑠

𝑞𝑊𝑁 x = 𝑞 x0 𝑞 x0 → x1 𝑄 | x2 − x2

∗ | < 𝑠

𝑞 x3 𝑞(x3 → x2)

Light vertex Camera vertex

x2

∗

Vertex merging Vertex connection

x2

∗

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x0 x3 x2

∗

x1 x2 𝑠

Light vertex Camera vertex

𝐽 = 𝑔

𝑘 x

𝑞𝑊𝑁 x = . . . = ΔW x2 𝑔

𝑠(x3 ← x2, x2 ∗ → x1)

𝜌𝑠2 ΔΦ(x2

∗)

cumulative importance photon flux

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x0 x1 x2 x4 x3 x0 x1 x2 x4 x3 x0 x1 x2 x4 x3 x3

∗

Unidirectional 2 ways Vertex connection 4 ways Vertex merging 5 ways Total 11 ways

Light vertex Camera vertex

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Stage 1: Light sub-path sampling

b) Connect to eye c) Build search structure a) Trace sub-paths

Stage 2: Eye sub-path sampling (reduced radius at each iteration)

a) Vertex connection VC b) Vertex merging VM c) Continue sub-path

VC VM

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Reference BDPT+VM BDPT PPM

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PPM PT BDPT VM

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VM

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VM+BDPT

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BPT PPM

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BPT PPM

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BPT PPM

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PT BDPT PPM BDPT+VM

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BDPT+VM

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BDPT+VM

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BDPT+VM

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