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We propose an approach for imaging in scattering media when large and diverse data sets are available. It has two steps. Using a dictionary learning algorithm the first step estimates the true Green's function vectors as columns in an…

Computer Vision and Pattern Recognition · Computer Science 2023-10-23 Miguel Moscoso , Alexei Novikov , George Papanicolaou , Chrysoula Tsogka

We design an algorithm which finds an $\epsilon$-approximate stationary point (with $\|\nabla F(x)\|\le \epsilon$) using $O(\epsilon^{-3})$ stochastic gradient and Hessian-vector products, matching guarantees that were previously available…

Machine Learning · Computer Science 2020-06-25 Yossi Arjevani , Yair Carmon , John C. Duchi , Dylan J. Foster , Ayush Sekhari , Karthik Sridharan

A new code for evaluation of light absorption and scattering by interstellar dust grains is presented. The radiative transfer problem is solved using ray-tracing algorithm in a self-consistent and highly efficient way. The code demonstrates…

Astrophysics · Physics 2007-05-23 D. Semionov , V. Vansevicius

We present a new numerical method for calculating the transfer of ionizing radiation, called C^2-Ray=Conservative, Causal Ray-tracing method. The method is explicitly photon-conserving, so the depletion of ionizing photons by bound-free…

Astrophysics · Physics 2009-11-11 Garrelt Mellema , Ilian T. Iliev , Marcelo A. Alvarez , Paul R. Shapiro

We propose a scheme to detect the diffusive cloak proposed by Schittny et al [Science 345, 427 (2014)]. We exploit the fact that diffusion of light is an approximation that disregards wave interference. The long-range contribution to…

Optics · Physics 2016-08-11 Milan Koirala , Alexey Yamilov

In this paper, we propose a Dimension-Reduced Second-Order Method (DRSOM) for convex and nonconvex (unconstrained) optimization. Under a trust-region-like framework, our method preserves the convergence of the second-order method while…

Optimization and Control · Mathematics 2023-07-04 Chuwen Zhang , Dongdong Ge , Chang He , Bo Jiang , Yuntian Jiang , Yinyu Ye

A new two-dimensional axi-symmetric ultraviolet radiative transfer code is presented, which is used to calculate photodissociation and ionization rates for use in chemistry models of flaring circumstellar disks. Scattering and absorption of…

Calculations of the opacity of hot, dense matter require models for plasma line broadening. However, the most general theories are too complex to calculate directly and some approximation is inevitably required. The most widely-used…

Plasma Physics · Physics 2020-10-05 R. A. Baggott , S. J. Rose , S. P. D. Mangles

The ability to see around corners, i.e., recover details of a hidden scene from its reflections in the surrounding environment, is of considerable interest in a wide range of applications. However, the diffuse nature of light reflected from…

We present a numerical implementation of radiative transfer based on an explicitly photon-conserving advection scheme, where radiative fluxes over the cell interfaces of a structured or unstructured mesh are calculated with a second-order…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Margarita Petkova , Volker Springel

We consider the reflection from a random medium of light with short coherence length. We found that the second order correlation function of light can have a peak in a direction where the reflection angle is equal to angle of incidence.…

Mesoscale and Nanoscale Physics · Physics 2020-12-24 A. Yu. Zyuzin

In this work, we present a comprehensive and comparative analysis of two detection modalities, i.e., polarization rotation and absorption measurement of light, for a double resonance alignment based optical magnetometer (DRAM). We derive…

Optics · Physics 2024-03-11 A. Akbar , M. Kozbiál , L. Elson , A. Meraki , J. Kolodyński , K. Jensen

In this paper we present two efficient implementations of the diffusion approximation to be employed in Monte Carlo computations of radiative transfer in dusty media of massive circumstellar disks. The aim is to improve the accuracy of the…

Instrumentation and Methods for Astrophysics · Physics 2009-11-13 M. Min , C. P. Dullemond , C. Dominik , A. de Koter , J. W. Hovenier

In view synthesis, a neural radiance field approximates underlying density and radiance fields based on a sparse set of scene pictures. To generate a pixel of a novel view, it marches a ray through the pixel and computes a weighted sum of…

Computer Vision and Pattern Recognition · Computer Science 2024-03-05 Nikita Morozov , Denis Rakitin , Oleg Desheulin , Dmitry Vetrov , Kirill Struminsky

Occlusion is one of the most challenging problems in depth estimation. Previous work has modeled the single-occluder occlusion in light field and get good results, however it is still difficult to obtain accurate depth for multi-occluder…

Computer Vision and Pattern Recognition · Computer Science 2017-11-22 Hao Zhu , Qing Wang , Jingyi Yu

Scattering hinders the passage of light through random media and consequently limits the usefulness of optical techniques for sensing and imaging. Thus, methods for increasing the transmission of light through such random media are of…

Optics · Physics 2014-06-23 Curtis Jin , Raj Rao Nadakuditi , Eric Michielssen , Stephen Rand

Directly regressing all 6 degrees-of-freedom (6DoF) for the object pose (e.g. the 3D rotation and translation) in a cluttered environment from a single RGB image is a challenging problem. While end-to-end methods have recently demonstrated…

Computer Vision and Pattern Recognition · Computer Science 2021-08-20 Yan Di , Fabian Manhardt , Gu Wang , Xiangyang Ji , Nassir Navab , Federico Tombari

Second-order coding rate of channel coding is discussed for general sequence of channels. The optimum second-order transmission rate with a constant error constraint $\epsilon$ is obtained by using the information spectrum method. We apply…

Information Theory · Computer Science 2016-11-15 Masahito Hayashi

In computational imaging, hardware for signal sampling and software for object reconstruction are designed in tandem for improved capability. Examples of such systems include computed tomography (CT), magnetic resonance imaging (MRI), and…

Image and Video Processing · Electrical Eng. & Systems 2022-11-01 Andrew Olsen , Yolanda Hu , Vidya Ganapati

Rendering volumetric scattering media, including clouds, fog, smoke, and other complex materials, is crucial for realism in computer graphics. Traditional path tracing, while unbiased, requires many long path samples to converge in scenes…

Graphics · Computer Science 2024-04-19 Becky Hu , Xi Deng , Fujun Luan , Miloš Hašan , Steve Marschner