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

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

Unidirectional sampling Vertex connection Density estimation Bidirectional path tracing Photon mapping

x 𝑙 x 0 𝑘 x 𝑒𝜈(x ) 𝐽 𝑘 = න 𝑔 x 𝑙−1 x 1 Ω 𝑘 = 𝑔 𝑘 x 𝑞 x = 𝑞 x 0 𝑞 x 1 … 𝑞 x 𝑙 𝐽 𝑞 x

x 1 x 3 x 0 x 2

Light vertex Camera vertex x 1 x 3 x 0 x 2

Light vertex Camera vertex x 1 x 1 x 3 x 3 x 0 x 0 x 2 x 2 Bidirectional path tracing Photon mapping

Light vertex Camera vertex x 1 x 1 x 3 x 3 x 0 x 0 𝑠 ∗ ∗ x 2 x 2 x 2 x 2 Bidirectional path tracing Vertex connection Photon mapping Vertex merging ∗ 𝜌𝑠 2 ∗ | < 𝑠 𝑞 𝑊𝐷 x = 𝑞 x 0 𝑞 x 0 → x 1 𝑞 𝑊𝑁 x = 𝑞 x 0 𝑞 x 0 → x 1 𝑄 | x 2 − x 2 𝑞 𝑊𝑁 x ≈ 𝑞 x 0 𝑞 x 0 → x 1 𝑞 x 1 → x 2 𝑞 𝑊𝑁 x = 𝑞 x 3 𝑞(x 3 → x 2 ) 𝑞(x 3 )𝑞 x 3 → x 2 𝑞 x 3 𝑞(x 3 → x 2 )

Light vertex Camera vertex cumulative importance photon flux ∗ → x 1 ) 𝑠 (x 3 ← x 2 , x 2 𝐽 = 𝑔 𝑘 x 𝑔 ∗ ) 𝑞 𝑊𝑁 x = . . . = ΔW x 2 ΔΦ(x 2 𝜌𝑠 2 x 1 x 3 x 0 𝑠 ∗ x 2 x 2

Light vertex Camera vertex x 4 x 0 Unidirectional 2 ways x 3 x 1 x 2 x 4 x 0 Vertex connection 4 ways x 3 x 1 x 2 x 4 x 0 Vertex merging 5 ways ∗ x 1 x 3 x 3 x 2 Total 11 ways

Stage 1: Light sub-path sampling a) Trace sub-paths b) Connect to eye c) Build search structure Stage 2: Eye sub-path sampling (reduced radius at each iteration) VC VC VM VM a) Vertex connection b) Vertex merging c) Continue sub-path

Reference BDPT BDPT+VM PPM

PT BDPT PPM VM

VM

VM+BDPT

PPM BPT

PPM BPT

PPM BPT

PT BDPT PPM BDPT+VM

BDPT+VM

BDPT+VM

BDPT+VM

BDPT