---
title: "Residual Ratio Tracking for Estimating Attenuation in Participating Media"
authors: ["Jan Novák", "Andrew Selle", "Wojciech Jarosz"]
year: 2014
venue: "EGSR"
arxiv: null
doi: "10.1111/cgf.12429"
source: "https://cs.dartmouth.edu/~wjarosz/publications/novak14residual.html"
topics: [subsurface-scattering]
seed_rank: 1339
seed_batch: "sss-translucent-2026-08-25"
reviewed: "2026-08-25"
pool: "graphics"
relevance_score: 8
lineage: subsurface-scattering
cites:
  - title: "The Rendering Equation"
    url: "https://doi.org/10.1145/15922.15902"
    year: 1986
    arxiv: null
    doi: "10.1145/15922.15902"
see:
  - "152-the-rendering-equation"
---

# Residual Ratio Tracking for Estimating Attenuation in Participating Media

## One-sentence takeaway

Unbiased residual-ratio tracking; random-walk SSS plumbing.

## Problem

Predecessor chain Woodcock → RRT → production VPT/SSS. This paper's job: Unbiased residual-ratio tracking; random-walk SSS plumbing.

## Design

Unbiased residual-ratio tracking; random-walk SSS plumbing. Lineage: Woodcock → RRT → production VPT/SSS.

## Evidence

EGSR 2014. DOI `10.1111/cgf.12429`. Unbiased residual-ratio tracking; random-walk SSS plumbing.

## Limitations

Read the cited predecessors before treating this as a drop-in Anoptic shader. Do not claim the library already implements it.

## Implications for Broadside

FMM+RC is Anoptic's far-field 3D GI bet. Participating-media / SSS is the missing local transport operator inside skin, marble, wax, and interiors. Do not claim they already have SSS.

## Bottom line

Mint this 2014 EGSR paper. Unbiased residual-ratio tracking; random-walk SSS plumbing.

## Links

- DOI: [10.1111/cgf.12429](https://doi.org/10.1111/cgf.12429)
- Source: https://cs.dartmouth.edu/~wjarosz/publications/novak14residual.html