Perceptual Navigation in Absorption-Scattering Space

2021 ◽  
Vol 2021 (29) ◽  
pp. 328-333
Author(s):  
Davit Gigilashvili ◽  
Philipp Urban ◽  
Jean-Baptiste Thomas ◽  
Marius Pedersen ◽  
Jon Yngve Hardeberg
Keyword(s):  
Uniform Space ◽  
Light Transport ◽  
Viewing Condition ◽  
Scattering Coefficients ◽  
Grid Optimization ◽  
New Space ◽  
Euclidean Distances ◽  
Subsurface Light

Translucency optically results from subsurface light transport and plays a considerable role in how objects and materials appear. Absorption and scattering coefficients parametrize the distance a photon travels inside the medium before it gets absorbed or scattered, respectively. Stimuli produced by a material for a distinct viewing condition are perceptually non-uniform w.r.t. these coefficients. In this work, we use multi-grid optimization to embed a non-perceptual absorption-scattering space into a perceptually more uniform space for translucency and lightness. In this process, we rely on A (alpha) as a perceptual translucency metric. Small Euclidean distances in the new space are roughly proportional to lightness and apparent translucency differences measured with A. This makes picking A more practical and predictable, and is a first step toward a perceptual translucency space.

scholarly journals Simulation of Light Distribution in Gamma Irradiated UHMWPE Using Monte Carlo Model for Light (MCML) Transport in Turbid Media: Analysis for Industrial Scale Biomaterial Modifications

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3039
Author(s):  
Ali Rizwan ◽  
Muhammad Saleem ◽  
Suhail H. Serbaya ◽  
Hemaid Alsulami ◽  
Aqsa Ghazal ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Optical Properties ◽  
Monte Carlo Model ◽  
Media Analysis ◽  
Light Distribution ◽  
Light Transport ◽  
Photon Absorption ◽  
Industrial Scale ◽  
Scattering Coefficients ◽  
Gamma Irradiated

(1) Background: This study investigated the miscibility of carbon-based fillers within industrial scale polymers for the preparation of superior quality polymer composites. It focuses on finding the light distribution in gamma irradiated ultra-high molecular weight polyethylene (UHMWPE). (2) Methods: The Kubleka–Munk model (KMM) was used to extract the optical properties, i.e., absorption coefficients (μa) and scattering coefficients (μs). Samples amounting to 30 kGy and 100 kGy of irradiated (in the open air) UHMWPE from 630 nm to 800 nm were used for this purpose. Moreover, theoretical validation of experimental results was performed while using extracted optical properties as inputs for the Monte Carlo model of light transport (MCML) code. (3) Conclusions: The investigations revealed that there was a significant decrease in absorption and scattering coefficient (μa & μs) values with irradiation, and 30 kGy irradiated samples suffered more compared to 100 kGy irradiated samples. Furthermore, the simulation of light transport for 800 nm showed an increase in penetration depth for UHMWPE after gamma irradiation. The decrease in dimensionless transport albedo  μs(μa+μs) from 0.95 to 0.93 was considered responsible for this increase in photon absorption per unit area with irradiation. The report results are of particular importance when considering the light radiation (from 600 nm to 899 nm) for polyethylene modification and/or stabilization via enhancing the polyethylene chain mobility.

scholarly journals The Role of Subsurface Scattering in Glossiness Perception

2021 ◽  
Vol 18 (3) ◽  
pp. 1-26
Author(s):  
Davit Gigilashvili ◽  
Weiqi Shi ◽  
Zeyu Wang ◽  
Marius Pedersen ◽  
Jon Yngve Hardeberg ◽  
...  
Keyword(s):  
Visual Cues ◽  
Light Transmission ◽  
Light Transport ◽  
Future Research ◽  
Subsurface Scattering ◽  
Visual Appearance ◽  
Material Appearance ◽  
Related Quality ◽  
The Difference ◽  
Subsurface Light

This study investigates the potential impact of subsurface light transport on gloss perception for the purposes of broadening our understanding of visual appearance in computer graphics applications. Gloss is an important attribute for characterizing material appearance. We hypothesize that subsurface scattering of light impacts the glossiness perception. However, gloss has been traditionally studied as a surface-related quality and the findings in the state-of-the-art are usually based on fully opaque materials, although the visual cues of glossiness can be impacted by light transmission as well. To address this gap and to test our hypothesis, we conducted psychophysical experiments and found that subjects are able to tell the difference in terms of gloss between stimuli that differ in subsurface light transport but have identical surface qualities and object shape. This gives us a clear indication that subsurface light transport contributes to a glossy appearance. Furthermore, we conducted additional experiments and found that the contribution of subsurface scattering to gloss varies across different shapes and levels of surface roughness. We argue that future research on gloss should include transparent and translucent media and to extend the perceptual models currently limited to surface scattering to more general ones inclusive of subsurface light transport.

scholarly journals Measuring isotropic subsurface light transport

2014 ◽  
Vol 22 (8) ◽  
pp. 9048 ◽  
Author(s):  
Kathrin Happel ◽  
Edgar Dörsam ◽  
Philipp Urban
Keyword(s):  
Light Transport ◽  
Subsurface Light

Green's function solution to subsurface light transport for BRDF computation

2013 ◽  
Author(s):  
Charly Collin ◽  
Ke Chen ◽  
Ajit Hakke-Patil ◽  
Sumanta Pattanaik ◽  
Kadi Bouatouch
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Light Transport ◽  
Function Solution ◽  
Subsurface Light

scholarly journals Propagation in waveguides with varying cross section and curvature: a new light on the role of supplementary modes in multi-modal methods

2014 ◽  
Vol 470 (2166) ◽  
pp. 20140008 ◽  
Author(s):  
Agnès Maurel ◽  
Jean-François Mercier ◽  
Simon Félix
Keyword(s):  
Boundary Conditions ◽  
Cross Section ◽  
Series Representation ◽  
Virtual Space ◽  
Scattering Problems ◽  
Scattering Coefficients ◽  
Wide Range ◽  
New Space ◽  
Modal Method

We present an efficient multi-modal method to describe the acoustic propagation in waveguides with varying curvature and cross section. A key feature is the use of a flexible geometrical transformation to a virtual space in which the waveguide is straight and has unitary cross section. In this new space, the pressure field has to satisfy a modified wave equation and associated modified boundary conditions. These boundary conditions are in general not satisfied by the Neumann modes, used for the series representation of the field. Following previous work, an improved modal method (MM) is presented, by means of the use of two supplementary modes. Resulting increased convergences are exemplified by comparison with the classical MM. Next, the following question is addressed: when the boundary conditions are verified by the Neumann modes, does the use of supplementary modes improve or degrade the convergence of the computed solution? Surprisingly, although the supplementary modes degrade the behaviour of the solution at the walls, they improve the convergence of the wavefield and of the scattering coefficients. This sheds a new light on the role of the supplementary modes and opens the way for their use in a wide range of scattering problems.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

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