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We present a generalization of the coupled dipole method to the scattering of light by arbitrary periodic structures. This new formulation of the coupled dipole method relies on the same direct-space discretization scheme that is widely…

Optics · Physics 2009-11-10 Patrick C. Chaumet , Adel Rahmani , Garnett W. Bryant

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

We propose a strategy for improving camera location estimation in structure from motion. Our setting assumes highly corrupted pairwise directions (i.e., normalized relative location vectors), so there is a clear room for improving current…

Computer Vision and Pattern Recognition · Computer Science 2019-01-24 Yunpeng Shi , Gilad Lerman

Iterative phase retrieval algorithms are widely used in digital optics for their efficiency and simplicity. Conventionally, these algorithms do not consider aberrations as they assume an ideal, aberration-free optical system. Here, we…

Optics · Physics 2025-02-10 Dylan Brault , Corinne Fournier , Tatiana Latychevskaia

In order to track the moving objects in long range against occlusion, interruption, and background clutter, this paper proposes a unified approach for global trajectory analysis. Instead of the traditional frame-by-frame tracking, our…

Computer Vision and Pattern Recognition · Computer Science 2015-02-03 Liang Lin , Yongyi Lu , Yan Pan , Xiaowu Chen

When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. In- terference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made…

Generalized Polynomial Chaos (gPC) expansions are well established for forward uncertainty propagation in many application areas. Although the associated computational effort may be reduced in comparison to Monte Carlo techniques, for…

Computational Engineering, Finance, and Science · Computer Science 2023-07-26 Niklas Georg , Ulrich Römer

A two-point ray-tracing technique for 3D smoothly heterogeneous, weakly transversely-isotropic media is based on Fermat's principle and takes advantage of global Chebyshev approximation of both the model and curved rays. This approximation…

Geophysics · Physics 2019-02-07 Vladimir Grechka , George A. McMechan

The introduction of cheap RGB-D cameras, stereo cameras, and LIDAR devices has given the computer vision community 3D information that conventional RGB cameras cannot provide. This data is often stored as a point cloud. In this paper, we…

Computer Vision and Pattern Recognition · Computer Science 2018-10-22 Aleksandr Savchenkov , Andrew Davis , Xuan Zhao

In this paper, we investigate the problem of coordinated path following for fixed-wing UAVs with speed constraints in 2D plane. The objective is to steer a fleet of UAVs along the path(s) while achieving the desired sequenced inter-UAV arc…

Systems and Control · Electrical Eng. & Systems 2020-05-12 Hao Chen , Yirui Cong , Xiangke Wang , Xin Xu , Lincheng Shen

Ptychography is a popular imaging technique that combines diffractive imaging with scanning microscopy. The technique consists of a coherent beam that is scanned across an object in a series of overlapping positions, leading to reliable and…

Numerical Analysis · Mathematics 2019-02-20 Samy Wu Fung , Zichao Di

Compressed sensing (CS) is a powerful method routinely employed to accelerate image acquisition. It is particularly suited to situations when the image under consideration is sparse but can be sampled in a basis where it is non-sparse. Here…

Image and Video Processing · Electrical Eng. & Systems 2022-07-18 Xudong Lv , Ashok Ajoy

Tomography is an imaging technique that works by reconstructing a scene from acquired data in the form of line integrals of the imaging domain. A fundamental underlying assumption in the reconstruction procedure is the precise alignment of…

Numerical Analysis · Mathematics 2018-07-13 Toby Sanders

Gated cameras hold promise as an alternative to scanning LiDAR sensors with high-resolution 3D depth that is robust to back-scatter in fog, snow, and rain. Instead of sequentially scanning a scene and directly recording depth via the photon…

Computer Vision and Pattern Recognition · Computer Science 2021-12-07 Amanpreet Walia , Stefanie Walz , Mario Bijelic , Fahim Mannan , Frank Julca-Aguilar , Michael Langer , Werner Ritter , Felix Heide

In this paper a new efficient algorithm for computation of radio wave ray trajectories is described. The algorithm is based on an original second-order difference scheme with a specific "length-conservation" property, which allows to…

Instrumentation and Methods for Astrophysics · Physics 2010-10-19 Leonid Benkevitch , Igor Sokolov , Divya Oberoi , Thomas Zurbuchen

Among recent developments centered around Randomized Kaczmarz (RK), a row-sampling iterative projection method for large-scale linear systems, several adaptions to the method have inspired faster convergence. Focusing solely on…

Numerical Analysis · Mathematics 2026-03-03 James Nguyen , Oleg Presnyakov , Adityakrishnan Radhakhrishnan

This paper presents a method to detect reflection of 3D light detection and ranging (Lidar) scans and uses it to classify the points and also map objects outside the line of sight. Our software uses several approaches to analyze the point…

Robotics · Computer Science 2020-10-28 Xiting Zhao , Zhijie Yang , Sören Schwertfeger

One of the most powerful approaches to imaging at the nanometer or subnanometer length scale is coherent diffraction imaging using X-ray sources. For amorphous (non-crystalline) samples, the raw data can be interpreted as the modulus of the…

Numerical Analysis · Mathematics 2020-04-02 Alexander Barnett , Charles L. Epstein , Leslie Greengard , Jeremy Magland

Characterizing the phase space distribution of particle beams in accelerators is a central part of accelerator understanding and performance optimization. However, conventional reconstruction-based techniques either use simplifying…

In this paper, we generalize proximal methods that were originally designed for convex optimization on normed vector space to non-convex pose graph optimization (PGO) on special Euclidean groups, and show that our proposed generalized…

Optimization and Control · Mathematics 2021-05-05 Taosha Fan , Todd Murphey