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In order to compute the Fourier transform of a function $f$ on the real line numerically, one samples $f$ on a grid and then takes the discrete Fourier transform. We derive exact error estimates for this procedure in terms of the decay and…

Numerical Analysis · Mathematics 2025-12-18 Martin Ehler , Karlheinz Gröchenig , Andreas Klotz

In this work we present an a priori error analysis for solving the unsteady advection equation on cut cell meshes along a straight ramp in two dimensions. The space discretization uses a lowest order upwind-type discontinuous Galerkin…

Numerical Analysis · Mathematics 2024-11-18 Gunnar Birke , Christian Engwer , Jan Giesselmann , Sandra May

This paper presents a novel line-aware rectification network (LaRecNet) to address the problem of fisheye distortion rectification based on the classical observation that straight lines in 3D space should be still straight in image planes.…

Computer Vision and Pattern Recognition · Computer Science 2020-03-26 Zhu-Cun Xue , Nan Xue , Gui-Song Xia

Computed Tomography (CT) is an essential non-destructive three dimensional imaging modality used in medicine, security screening, and inspection of manufactured components. Typical CT data acquisition entails the collection of a thousand or…

Medical Physics · Physics 2024-10-11 Kyle M. Champley , Michael B. Zellner , Joseph W. Tringe , Harry E. Martz

Ultrasound reflection tomography is widely used to image large complex specimens that are only accessible from a single side, such as well systems and nuclear power plant containment walls. Typical methods for inverting the measurement rely…

Image and Video Processing · Electrical Eng. & Systems 2018-10-01 Hani Almansouri , S. V. Venkatakrishnan , Gregery T. Buzzard , Charles A. Bouman , Hector Santos-Villalobos

Dual-energy computed tomography (DECT) has shown great potential and promising applications in advanced imaging fields for its capabilities of material decomposition. However, image reconstructions and decompositions under sparse views…

Medical Physics · Physics 2016-08-01 Lei Li , Ailong Cai , Linyuan Wang , Bin Yan , Hanming Zhang , Zhizhong Zheng , Wenkun Zhang , Wanli Lu , Guoen Hu

The aim of this paper is to study the recovery of a spatially dependent potential in a (sub)diffusion equation from overposed final time data. We construct a monotone operator one of whose fixed points is the unknown potential. The…

Numerical Analysis · Mathematics 2022-01-06 Zhengqi Zhang , Zhidong Zhang , Zhi Zhou

Depth completion is crucial for many robotic tasks such as autonomous driving, 3-D reconstruction, and manipulation. Despite the significant progress, existing methods remain computationally intensive and often fail to meet the real-time…

Computer Vision and Pattern Recognition · Computer Science 2023-08-01 Tianan Li , Zhehan Chen , Huan Liu , Chen Wang

Inverse problems arise in a multitude of applications, where the goal is to recover a clean signal from noisy and possibly (non)linear observations. The difficulty of a reconstruction problem depends on multiple factors, such as the ground…

Image and Video Processing · Electrical Eng. & Systems 2024-08-21 Zalan Fabian , Berk Tinaz , Mahdi Soltanolkotabi

In this paper, we study the mathematical imaging problem of diffraction tomography (DT), which is an inverse scattering technique used to find material properties of an object by illuminating it with probing waves and recording the…

Numerical Analysis · Mathematics 2023-05-16 Florian Faucher , Clemens Kirisits , Michael Quellmalz , Otmar Scherzer , Eric Setterqvist

Tomography is a central tool in medical applications, allowing doctors to investigate patients' interior features. The Radon transform (in two dimensions) is commonly used to model the measurement process in parallel-beam CT. Suitable…

Numerical Analysis · Mathematics 2026-02-27 Richard Huber

The principles of difference imaging outlined and the technique of Alard and Lupton (1997) is generalised to generate the best possible difference images to within the limits of measurement error. It is shown how for a large database of…

Astrophysics · Physics 2007-05-23 Austin B. Tomaney

We show that $C^0$-fine approximation of convex functions by smooth (or real analytic) convex functions on $\R^d$ is possible in general if and only if $d=1$. Nevertheless, for $d\geq 2$ we give a characterization of the class of convex…

Classical Analysis and ODEs · Mathematics 2012-01-24 Daniel Azagra

Depth acquisition, based on active illumination, is essential for autonomous and robotic navigation. LiDARs (Light Detection And Ranging) with mechanical, fixed, sampling templates are commonly used in today's autonomous vehicles. An…

Computer Vision and Pattern Recognition · Computer Science 2019-08-06 Adam Wolff , Shachar Praisler , Ilya Tcenov , Guy Gilboa

Structure from Motion (SfM) often fails to estimate accurate poses in environments that lack suitable visual features. In such cases, the quality of the final 3D mesh, which is contingent on the accuracy of those estimates, is reduced. One…

Computer Vision and Pattern Recognition · Computer Science 2021-04-08 Victor Amblard , Timothy P. Osedach , Arnaud Croux , Andrew Speck , John J. Leonard

This paper presents a new system to obtain dense object reconstructions along with 6-DoF poses from a single image. Geared towards high fidelity reconstruction, several recent approaches leverage implicit surface representations and deep…

Computer Vision and Pattern Recognition · Computer Science 2020-04-28 Aniket Pokale , Aditya Aggarwal , K. Madhava Krishna

Despite the increasing prevalence of rotating-style capture (e.g., surveillance cameras), conventional stereo rectification techniques frequently fail due to the rotation-dominant motion and small baseline between views. In this paper, we…

Computer Vision and Pattern Recognition · Computer Science 2023-07-12 Yongcong Zhang , Yifei Xue , Ming Liao , Huiqing Zhang , Yizhen Lao

In this paper we study reconstruction of a function $f$ from its discrete Radon transform data in $\mathbb R^3$ when $f$ has jump discontinuities. Consider a conventional parametrization of the Radon data in terms of the affine and angular…

Numerical Analysis · Mathematics 2019-03-21 Alexander Katsevich

Discrete-velocity approximations represent a popular way for computing the Boltzmann collision operator. The direct numerical evaluation of such methods involve a prohibitive cost, typically $O(N^{2d+1})$ where $d$ is the dimension of the…

Numerical Analysis · Mathematics 2014-01-15 Clément Mouhot , Lorenzo Pareschi , Thomas Rey

In the usual trace reconstruction problem, the goal is to exactly reconstruct an unknown string of length $n$ after it passes through a deletion channel many times independently, producing a set of traces (i.e., random subsequences of the…

Data Structures and Algorithms · Computer Science 2020-12-17 Sami Davies , Miklos Z. Racz , Cyrus Rashtchian , Benjamin G. Schiffer
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