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We show that on a two-dimensional compact nontrapping Riemannian manifold with strictly convex boundary, a piecewise constant function can be recovered from its integrals over geodesics. We adapt the injectivity proof which uses variations…

Differential Geometry · Mathematics 2020-01-20 Vadim Lebovici

We study the problem of recovering a function on a pseudo-Riemannian manifold from its integrals over all null geodesics in three geometries: pseudo-Riemannian products of Riemannian manifolds, Minkowski spaces and tori. We give proofs of…

Differential Geometry · Mathematics 2016-08-11 Joonas Ilmavirta

We prove the local invertibility, up to potential fields, and stability of the geodesic X-ray transform on tensor fields of order 1 and 2 near a strictly convex boundary point, on manifolds with boundary of dimension n>=3. We also present…

Differential Geometry · Mathematics 2014-10-21 Plamen Stefanov , Gunther Uhlmann , András Vasy

We consider spaces of smooth immersed plane curves (modulo translations and/or rotations), equipped with reparameterization invariant weak Riemannian metrics involving second derivatives. This includes the full $H^2$-metric without zero…

Differential Geometry · Mathematics 2015-11-12 Martin Bauer , Martins Bruveris , Peter W. Michor

We consider the inverse problem of the broken ray transform (sometimes also referred to as the V-line transform). Explicit image reconstruction formulas are derived and tested numerically. The obtained formulas are generalizations of the…

Mathematical Physics · Physics 2011-01-07 Lucia Florescu , Vadim A. Markel , John C. Schotland

The paper discusses numerical implementations of various inversion schemes for generalized V-line transforms on vector fields introduced in [6]. It demonstrates the possibility of efficient recovery of an unknown vector field from five…

Numerical Analysis · Mathematics 2023-11-20 Gaik Ambartsoumian , Mohammad Javad Latifi Jebelli , Rohit Kumar Mishra

This article surveys recent results aiming at obtaining refined mapping estimates for the X-ray transform on a Riemannian manifold with boundary, which leverage the condition that the boundary be strictly geodesically convex. These…

Analysis of PDEs · Mathematics 2023-09-04 François Monard

Let $\bbK=\mathbb R, \mathbb C, \mathbb H$ be the field of real, complex or quaternionic numbers and $M_{p, q}(\bbK)$ the vector space of all $p\times q$-matrices. Let $X$ be the matrix unit ball in $M_{n-r, r}(\bbK)$ consisting of…

Functional Analysis · Mathematics 2007-11-12 Genkai Zhang

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

Given a Lorentzian manifold, the light ray transform of a function is its integrals along null geodesics. This paper is concerned with the injectivity of the light ray transform on functions and tensors, up to the natural gauge for the…

Analysis of PDEs · Mathematics 2023-05-10 Ali Feizmohammadi , Joonas Ilmavirta , Lauri Oksanen

New simple proofs are given to some elementary approximate and explicit inversion formulas for Riesz potentials. The results are applied to reconstruction of functions from their integrals over Euclidean planes in integral geometry.

Functional Analysis · Mathematics 2011-01-27 Boris Rubin

We develop a geometric version of the inverse problem of the calculus of variations for discrete mechanics and constrained discrete mechanics. The geometric approach consists of using suitable Lagrangian and isotropic submanifolds. We also…

Differential Geometry · Mathematics 2018-05-09 María Barbero-Liñán , Marta Farré Puiggalí , Sebastián Ferraro , David Martín de Diego

This paper sheds light on the essential characteristics of geodesics, which frequently occur in considerations from motion in Euclidean space. Focus is mainly on a method of obtaining them from the calculus of variations, and an explicit…

General Mathematics · Mathematics 2017-03-21 Uchechukwu Michael Opara

We study the geodesics on an invariant surface of a three dimensional Riemannian manifold. The main results are: the characterization of geodesic orbits; a Clairaut's relation and its geometric interpretation in some remarkable three…

Differential Geometry · Mathematics 2009-12-03 Stefano Montaldo , Irene I. Onnis

We show that the geodesic ray transform is injective on scalar functions on spherically symmetric reversible Finsler manifolds where the Finsler norm satisfies a Herglotz condition. We use angular Fourier series to reduce the injectivity…

Differential Geometry · Mathematics 2022-12-06 Joonas Ilmavirta , Keijo Mönkkönen

Consider a compact Riemannian manifold in dimension $n\geq 3$ with strictly convex boundary. We show that the transverse ray transform of $1$ tensors and the mixed ray transform of $1+1$ tensors are invertible, up to natural obstructions,…

Differential Geometry · Mathematics 2024-01-18 Gunther Uhlmann , Jian Zhai

Consider a Riemannian manifold in dimension $n\geq 3$ with strictly convex boundary. We prove the local invertibility, up to potential fields, of the geodesic ray transform on tensor fields of rank four near a boundary point. This problem…

Differential Geometry · Mathematics 2020-01-08 Maarten V. de Hoop , Gunther Uhlmann , Jian Zhai

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 initiate the study of X-ray tomography on sub-Riemannian manifolds, for which the Heisenberg group exhibits the simplest nontrivial example. With the language of the group Fourier Transform, we prove an operator-valued incarnation of the…

Differential Geometry · Mathematics 2020-10-22 Steven Flynn

Algorithms for the computation of the forward and inverse geodesic problems for an ellipsoid of revolution are derived. These are accurate to better than 15 nm when applied to the terrestrial ellipsoids. The solutions of other problems…

Geophysics · Physics 2015-03-18 Charles F. F. Karney