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For the first time, a globally convergent numerical method is developed and Lipschitz stability estimate is obtained for the challenging problem of travel time tomography in 3D for formally determined incomplete data. The semidiscrete case…

Numerical Analysis · Mathematics 2019-04-16 Michael V. Klibanov

Concatenated backward ray mapping is an alternative for ray tracing in 2D. It is based on the phase-space description of an optical system. Phase space is the set of position and direction coordinates of light rays intersecting a surface.…

Magnetic field inhomogeneity estimation is important in some types of magnetic resonance imaging (MRI), including field-corrected reconstruction for fast MRI with long readout times, and chemical shift based water-fat imaging. Regularized…

Image and Video Processing · Electrical Eng. & Systems 2020-10-13 Claire Yilin Lin , Jeffrey A. Fessler

This paper considers wave-based imaging through a heterogeneous (random) scattering medium. The goal is to estimate the support of the reflectivity function of a remote scene from measurements of the backscattered wave field. The proposed…

Image and Video Processing · Electrical Eng. & Systems 2021-05-27 Liliana Borcea , Josselin Garnier

Ray tracing algorithms, that can simulate multipath radio propagation in presence of geometric obstacles such as buildings, objects or vehicles, are becoming quite popular, due to the increasing availability of digital environment databases…

Signal Processing · Electrical Eng. & Systems 2023-06-14 Denis Bilibashi , Enrico M. Vitucci , Vittorio Degli-Esposti

The Fermat principle is advocated to be a convenient tool to analyze the light propagation in a curved space time. It is shown that in the weak deflection regime the light ray trajectories can be systematically described by applying the…

General Relativity and Quantum Cosmology · Physics 2025-04-03 Joanna Piwnik , Joanna Gonera , Piotr Kosinski

A novel method which is called the Chebyshev inertial iteration for accelerating the convergence speed of fixed-point iterations is presented. The Chebyshev inertial iteration can be regarded as a valiant of the successive over relaxation…

Optimization and Control · Mathematics 2021-06-09 Tadashi Wadayama , Satoshi Takabe

This paper investigates the point convergence of accelerated gradient methods for multiobjective optimization, in both continuous and discrete settings. We address the open problems of whether the solution trajectory of the multiobjective…

Optimization and Control · Mathematics 2025-11-14 Yingdong Yin

Accurate 3D multi-object tracking (MOT) is vital for autonomous vehicles, yet LiDAR and camera-based methods degrade in adverse weather. Meanwhile, Radar-based solutions remain robust but often suffer from limited vertical resolution and…

Computer Vision and Pattern Recognition · Computer Science 2025-02-04 Dong-In Kim , Dong-Hee Paek , Seung-Hyun Song , Seung-Hyun Kong

We present a method to extract temporal hypergraphs from sequences of 2-dimensional functions obtained as solutions to Optimal Transport problems. We investigate optimality principles exhibited by these solutions from the point of view of…

Discrete Mathematics · Computer Science 2023-01-10 Diego Baptista , Caterina De Bacco

This paper considers a two-dimensional persistent monitoring problem by controlling movements of second-order agents to minimize some uncertainty metric associated with targets in a dynamic environment. In contrast to common sensing models…

Optimization and Control · Mathematics 2019-11-12 Yan-Wu Wang , Ming-Jie Zhao , Wu Yang , Nan Zhou , Christos G. Cassandras

The increasing use of microfluidics in industrial, biomedical, and clinical applications requires a more and more precise control of the microfluidic flows and suspended particles or cells. This leads to higher demands in three-dimensional…

Fluid Dynamics · Physics 2020-11-10 Massimiliano Rossi , Rune Barnkob

Accurate rail location is a crucial part in the railway support driving system for safety monitoring. LiDAR can obtain point clouds that carry 3D information for the railway environment, especially in darkness and terrible weather…

Computer Vision and Pattern Recognition · Computer Science 2022-08-10 Xinyi Yu , Weiqi He , Xuecheng Qian , Yang Yang , Linlin Ou

We propose a compact and efficient tetrahedral mesh representation to improve the ray-tracing performance. We reorder tetrahedral mesh data using a space-filling curve to improve cache locality. Most importantly, we propose an efficient ray…

Graphics · Computer Science 2021-03-04 Aytek Aman , Serkan Demirci , Uğur Güdükbay

In this work we introduce a novel algorithm for transient rendering in participating media. Our method is consistent, robust, and is able to generate animations of time-resolved light transport featuring complex caustic light paths in…

Graphics · Computer Science 2018-05-25 Julio Marco , Ibón Guillén , Wojciech Jarosz , Diego Gutierrez , Adrian Jarabo

We propose a method for designing refractive optical elements for collimated beam shaping. In this method, the problem of finding a ray mapping is formulated as a linear assignment problem, which is a discrete version of the corresponding…

Optical images of transparent three-dimensional objects can be different from a replica of the object's cross section in the image plane due to refraction at the surface or in the body of the object. Simulations of the object's image are…

We extend the result on the spectral projected gradient method by Birgin et al. in 2000 to a log-determinant semidefinite problem (SDP) with linear constraints and propose a spectral projected gradient method for the dual problem. Our…

Optimization and Control · Mathematics 2018-12-04 Takashi Nakagaki , Mituhiro Fukuda , Sunyoung Kim , Makoto Yamashita

We present a second-order gradient analysis of light transport in participating media and use this to develop an improved radiance caching algorithm for volumetric light transport. We adaptively sample and interpolate radiance from sparse…

Graphics · Computer Science 2018-05-24 Julio Marco , Adrian Jarabo , Wojciech Jarosz , Diego Gutierrez

This paper introduces a constructive method for approximating relative continuum measurements in two-dimensional electrical impedance tomography based on data originating from either the point electrode model or the complete electrode…

Numerical Analysis · Mathematics 2021-03-09 Henrik Garde , Nuutti Hyvönen