Rendering human skin using a multi-layer reflection model

A key element to creating realistic images is the appearance of surfaces. In order to overcome the artificial look of synthetic humans, human skin has to be modelled in all its variety. A new physically-based skin reflection model is presented in this paper to render a diverse selection of skin complexions. The reflection model is based on steady-state light transport theory in multi-layered skin tissue. A three-layer simulation model has been developed to capture the effect of natural sebum on skin appearance. Sebum is found over most parts of the body, causing skin to look more specular, depending on the viewing conditions. Optical and geometric properties are used as control parameters to influence the surface reflection and subsurface scattering of light within the three layers. The resultant reflection consists of the specular reflection due to the Fresnel effect, as well as the diffuse reflection from subsurface scattering. The Monte Carlo method isused to simulate the propagation of light in skin tissue. Various effects like scattering, absorption, reflection and transmission have been taken into account. The bi-directional reflectance distribution function (BRDF) obtained from the simulation is used to render the appearance of human skin. Comparisons between the simulated BRDF results and experimental measurements show that the physical simulation is highly realistic

An Introduction to Light Interaction with Human Skin

Despite the notable progress in physically-based rendering, there is still a long way to go before one can automatically generate predictable images of organic materials such as human skin. In this tutorial, the main physical and biological aspects involved in the processes of propagation and absorption of light by skin tissues are examined. These processes affect not only skin appearance, but also its health. For this reason, they have also been the object of study in biomedical research. The models of light interaction with human skin developed by the biomedical community are mainly aimed at the simulation of skin spectral properties which are used to determine the concentration and distribution of various substances. In computer graphics, the focus has been on the simulation of light scattering properties that affect skin appearance. Computer models used to simulate these spectral and scattering properties are described in this tutorial, and their strengths and limitations discussed. Keywords: natural phenomena, biologically and physically-based rendering

Digitally Yours; The Body in Contemporary Photography

This article analyses two artworks by contemporary photographers, Alexa Wright and Wendy McMurdo. It focuses in particular on the relationship between digital technologies and representation of the body, and on the changes to accepted paradigms of sexuality, identity and sensuousness caused by the computation of the art object. The article appears in ‘The Issues: In Contemporary Culture and Aesthetics’, which explores the intersecting fields of contemporary art, philosophy and practice

The effect of air gap entrapped in firefighter protective garment on thermal behaviour

Mestrado de dupla diplomação com a Hassiba Benbouali University of ChlefThe main objective of this work is to investigate the thermal protective performance (TPP) of firefighter’s garments under 10s/20s of various thermal exposures, shedding light on the effect of the air gap, the effect of fabric thickness and the radiant heat intensity (using Kevlar/PBI and Nomex fabrics) on skin burn predictions. The numerical simulations were performed using the ANSYS software in accordance with the temperature-dependent thermal properties of the materials. A numerical calculation model by finite elements is developed considering the blood perfusion rate. The model is validated against experimental tests and against numerical results from other authors. A parametric analysis was developed upon a set of 500 simulations. The results obtained are treated to evaluate and study the effect of the above-mentioned factors on TPP of firefighter’s garments and skin burn predictions. Finally, based on the numerical results determined for high flash fire and for high exposure time (20 s), a new proposal is presented to determine the time to reach the first, second and third-degree skin burn.O principal objetivo deste trabalho é investigar o desempenho de proteção térmica (TPP) de vestuário de bombeiros quando exposto durante 10s/20s a várias solicitações térmicas, analisando o efeito da camada de ar, o efeito da espessura do tecido e a intensidade de calor radiante (utilizando tecidos Kevlar/PBI e NOMEX) na previsão de queimadura da pele. As simulações numéricas foram realizadas utilizando o programa ANSYS, de acordo com as propriedades térmicas dependentes da temperatura dos materiais. Foi desenvolvido um modelo de cálculo numérico por elementos finitos, considerando a taxa de perfusão sanguínea. O modelo é validado em relação a testes experimentais e em relação a resultados numéricos de outros autores. Foi desenvolvido um estudo paramétrico, com base num conjunto de 500 simulações. Os resultados obtidos são tratados para avaliar e estudar o efeito dos fatores acima mencionados sobre o desempenho TPP do vestuário de bombeiros e previsões de queimaduras da pele. Finalmente, com base nos resultados numéricos determinados para exposições a elevados valores de radiação e para tempos de exposição elevados (20 s), é apresentada uma nova proposta para determinar o tempo para atingir queimaduras de primeiro, segundo e terceiro grau na pele

Aerospace medicine and biology: A continuing bibliography with indexes

This bibliography lists 161 reports, articles, and other documents introduced into the NASA scientific and technical information system in November, 1987

Deducing effective light transport parameters in optically thin systems

We present an extensive Monte Carlo study on light transport in optically thin slabs, addressing both axial and transverse propagation. We completely characterize the so-called ballistic-to-diffusive transition, notably in terms of the spatial variance of the transmitted/reflected profile. We test the validity of the prediction cast by diffusion theory, that the spatial variance should grow independently of absorption and, to a first approximation, of the sample thickness and refractive index contrast. Based on a large set of simulated data, we build a freely available look-up table routine allowing reliable and precise determination of the microscopic transport parameters starting from robust observables which are independent of absolute intensity measurements. We also present the Monte Carlo software package that was developed for the purpose of this study