# Study of diffuse scattering on facial surface using ray tracing approach

## TL;DR

This study uses ray tracing to show how skin texture affects light scattering, revealing that fine textures enhance the soft-focus effect and skin radiance.

## Contribution

A validated 2D model linking subvisible micro texture to skin optical properties is introduced, offering new insights for cosmetics and dermatology.

## Key findings

- The subvisible micro texture parameter $u_w/u_h$ strongly influences diffuse reflection and soft-focus effects on skin.
- Finer subvisible micro textures increase transversal light movement from inside to outside the skin.
- Macro texture has a less significant impact on light scattering compared to subvisible micro texture.

## Abstract

This study investigates the role of topographic attributes in light scattering and diffuse reflection on the skin surface, and diffuse transmission across the surface layer. Validated ray-tracing simulations establish a quantitative link between subvisible micro texture (SMT) and macro texture to skin optical properties, representing youthful and healthy skin characteristics. Our findings reveal the dominant role of the subvisible micro texture parameter (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$${u}_{w}/{u}_{h}$$\end{document}, the ratio of width to height) in governing light scattering. Smaller ratios, corresponding to fine SMT, result in increased diffuse reflection and create a more pronounced soft-focus effect, which plays a critical role in driving profound skin appearance such as radiance. While the macro texture parameter also influences scattering, its impact is less significant. Additionally, we quantify the impact of SMT on the transversal light movement from inside the skin to outside it. This simulation showed that more incident light leaves after traveling inside skin with smaller \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$${u}_{w}/{u}_{h}$$\end{document}, a measure of finer SMT. Our validated 2D subvisible micro texture model accurately computes the light-skin interactions influenced by the various levels of the skin’s topographic features, offering valuable insights for cosmetics, dermatology, and aesthetic medical imaging.