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The reconstruction problem of voxels with individual weightings can be modeled a position- and angle- dependent function in the forward-projection. This changes the system matrix and prohibits to use standard filtered backprojection. In…

Computer Vision and Pattern Recognition · Computer Science 2020-10-28 Lina Felsner , Tobias Würfl , Christopher Syben , Philipp Roser , Alexander Preuhs , Andreas Maier , Christian Riess

Image reconstruction under multiple light scattering is crucial in a number of applications such as diffraction tomography. The reconstruction problem is often formulated as a nonconvex optimization, where a nonlinear measurement model is…

Computer Vision and Pattern Recognition · Computer Science 2018-07-04 Yu Sun , Zhihao Xia , Ulugbek S. Kamilov

We study the geodesic X-ray transform $I_\Gamma$ of tensor fields on a compact Riemannian manifold $M$ with non-necessarily convex boundary and with possible conjugate points. We assume that $I_\Gamma$ is known for geodesics belonging to an…

Differential Geometry · Mathematics 2007-05-23 Plamen Stefanov , Gunther Uhlmann

In this paper we analyze the local and global boundary rigidity problem for general Riemannian manifolds with boundary $(M,g)$. We show that the boundary distance function, i.e., $d_g|_{\partial M\times\partial M}$, known near a point $p\in…

Differential Geometry · Mathematics 2021-05-13 Plamen Stefanov , Gunther Uhlmann , Andras Vasy

We consider the broken ray transform on Riemann surfaces in the presence of an obstacle, following earlier work of Mukhometov. If the surface has nonpositive curvature and the obstacle is strictly convex, we show that a function is…

Differential Geometry · Mathematics 2016-06-21 Joonas Ilmavirta , Mikko Salo

The geodesic ray transform, the mixed ray transform and the transverse ray transform of a tensor field on a manifold can all be seen as what we call mixing ray transforms, compositions of the geodesic ray transform and an invertible linear…

Differential Geometry · Mathematics 2024-09-10 Joonas Ilmavirta , Keijo Mönkkönen , Jesse Railo

We prove that the geodesic X-ray transform is injective on $L^2$ when the Riemannian metric is simple but the metric tensor is only finitely differentiable. The number of derivatives needed depends explicitly on dimension, and in dimension…

Analysis of PDEs · Mathematics 2023-09-25 Joonas Ilmavirta , Antti Kykkänen , Kelvin Lam

We first give a constructive answer to the attenuated tensor tomography problem on simple surfaces. We then use this result to propose two approaches to produce vector-valued integral transforms which are fully injective over tensor fields.…

Differential Geometry · Mathematics 2018-11-30 Venkateswaran P. Krishnan , Rohit Kumar Mishra , François Monard

We consider the X-ray transform in a projective space over a finite field. It is well known (after E. Bolker) that this transform is injective. We formulate an analog of I.M. Gelfand's admissibility problem for the Radon transform, which…

Metric Geometry · Mathematics 2017-07-26 David V. Feldman , Eric L. Grinberg

We present a general framework to study uniqueness, stability and reconstruction for infinite-dimensional inverse problems when only a finite-dimensional approximation of the measurements is available. For a large class of inverse problems…

Analysis of PDEs · Mathematics 2021-11-10 Giovanni S. Alberti , Matteo Santacesaria

We consider topological conditions under which a locally invertible map admits a global inverse. Our main theorem states that a local diffeomorphism $f: M \to\mathbb{R}^n$ is bijective if and only if $H_{n-1}(M)=0$ and the pre-image of…

Geometric Topology · Mathematics 2008-08-04 Eduardo Cabral Balreira

Reconstructing the unknown spectrum of a given X-ray source is a common problem in a wide range of X-ray imaging tasks. For high-energy sources, transmission measurements are mostly used to recover the X-ray spectrum, as a solution to an…

Applied Physics · Physics 2023-07-13 Arthur Walker , Alexandre Friou , Kevin Ginsburger

We consider the inverse problem of recovering a potential from the Dirichlet to Neumann map at a large fixed frequency on certain Riemannian manifolds. We extend the earlier result of [G. Uhlmann and Y. Wang, arXiv:2104.03477] to the case…

Analysis of PDEs · Mathematics 2023-09-01 Shiqi Ma , Suman Kumar Sahoo , Mikko Salo

The goal of inversion is to estimate the model which generates the data of observations with a specific modeling equation. One general approach to inversion is to use optimization methods which are algebraic in nature to define an objective…

Geophysics · Physics 2015-06-02 August Lau , Chuan Yin

In this paper we demonstrate a computational method to solve the inverse scattering problem for a star-shaped, smooth, penetrable obstacle in 2D. Our method is based on classical ideas from computational geometry. First, we approximate the…

Dix formulated the inverse problem of recovering an elastic body from the measurements of wave fronts of point sources. We geometrize this problem in the context of seismology, leading to the geometrical inverse problem of recovering a…

Differential Geometry · Mathematics 2025-03-14 Maarten V. de Hoop , Joonas Ilmavirta , Matti Lassas

In this work, we propose a new paradigm of iterative model-based reconstruction algorithms for providing real-time solution for zooming-in and refining a region of interest in medical and clinical tomographic images. This algorithmic…

Image and Video Processing · Electrical Eng. & Systems 2025-12-01 Junqi Tang , Guixian Xu , Jinglai Li

A rigorous mathematical model and an efficient computational method are proposed to solving the inverse elastic surface scattering problem which arises from the near-field imaging of periodic structures. We demonstrate how an enhanced…

Analysis of PDEs · Mathematics 2017-12-08 Huaian Diao , Peijun Li , Xiaokai Yuan

An inverse scattering problem is formulated for reconstructing optical properties of biological tissues. A recursive linearization algorithm is used to solve the inverse scattering problem. We employed the idea of finite element boundary…

Numerical Analysis · Mathematics 2014-04-30 Ying Li

Let X be a manifold equipped with a complete Riemannian metric of constant negative curvature and finite volume. We demonstrate the finiteness of the collection of totally geodesic immersed hypersurfaces in X that lie in the zero-level set…

Differential Geometry · Mathematics 2018-11-20 Chris Judge , Sugata Mondal