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An explicit series solution is proposed for the inversion of the spherical mean Radon transform. Such an inversion is required in problems of thermo- and photo- acoustic tomography. Closed-form inversion formulae are currently known only…

Analysis of PDEs · Mathematics 2009-11-13 Leonid Kunyansky

Estimating camera poses is a fundamental task for 3D reconstruction and remains challenging given sparsely sampled views (<10). In contrast to existing approaches that pursue top-down prediction of global parametrizations of camera…

Computer Vision and Pattern Recognition · Computer Science 2024-04-05 Jason Y. Zhang , Amy Lin , Moneish Kumar , Tzu-Hsuan Yang , Deva Ramanan , Shubham Tulsiani

Geometrically decorated two-dimensional (2D) discrete surfaces can be more effective than conventional smooth reflectors in managing wave radiation. Constructive non-specular wave scattering permits the scattering angle to be other than…

Practical applications of thermoacoustic tomography require numerical inversion of the spherical mean Radon transform with the centers of integration spheres occupying an open surface. Solution of this problem is needed (both in 2-D and…

Analysis of PDEs · Mathematics 2009-11-13 Leonid Kunyansky

Depth sensing devices have created various new applications in scientific and commercial research with the advent of Microsoft Kinect and PMD (Photon Mixing Device) cameras. Most of these applications require the depth cameras to be…

Computer Vision and Pattern Recognition · Computer Science 2017-09-11 Ramanpreet Singh Pahwa , Minh N. Do , Tian Tsong Ng , Binh-Son Hua

In this paper, we propose a novel projector-camera system for practical and low-cost acquisition of a dense object 3D model with the spectral reflectance property. In our system, we use a standard RGB camera and leverage an off-the-shelf…

Computer Vision and Pattern Recognition · Computer Science 2019-08-23 Chunyu Li , Yusuke Monno , Hironori Hidaka , Masatoshi Okutomi

Determining the position and orientation of a calibrated camera from a single image with respect to a 3D model is an essential task for many applications. When 2D-3D correspondences can be obtained reliably, perspective-n-point solvers can…

Computer Vision and Pattern Recognition · Computer Science 2019-06-19 Dylan Campbell , Lars Petersson , Laurent Kneip , Hongdong Li , Stephen Gould

Recovering dense 3D geometry from unposed images remains a foundational challenge in computer vision. Current state-of-the-art models are predominantly trained on perspective datasets, which implicitly constrains them to a standard pinhole…

Computer Vision and Pattern Recognition · Computer Science 2026-03-25 Namitha Guruprasad , Abhay Yadav , Cheng Peng , Rama Chellappa

We present explicit filtration/backprojection-type formulae for the inversion of the spherical (circular) mean transform with the centers lying on the boundary of some polyhedra (or polygons, in 2D). The formulae are derived using the…

Analysis of PDEs · Mathematics 2015-05-19 Leonid Kunyansky

In this paper, we consider a problem inspired by the real-world need to identify the topographical features of ocean basins. Specifically we consider the problem of estimating the bottom impermeable boundary to an inviscid, incompressible,…

Analysis of PDEs · Mathematics 2023-08-22 Vishal Vasan , Manisha , Didier Auroux

Recovering the 3D shape of transparent objects using a small number of unconstrained natural images is an ill-posed problem. Complex light paths induced by refraction and reflection have prevented both traditional and deep multiview stereo…

Computer Vision and Pattern Recognition · Computer Science 2020-07-24 Zhengqin Li , Yu-Ying Yeh , Manmohan Chandraker

Camera calibration involves estimating camera parameters to infer geometric features from captured sequences, which is crucial for computer vision and robotics. However, conventional calibration is laborious and requires dedicated…

Computer Vision and Pattern Recognition · Computer Science 2025-02-25 Kang Liao , Lang Nie , Shujuan Huang , Chunyu Lin , Jing Zhang , Yao Zhao , Moncef Gabbouj , Dacheng Tao

The MARS scanner is designed for the x-ray spectroscopic study of samples with the aid of computer tomography methods. Computer tomography allows the reconstruction of slices of an investigated sample using a set of shadow projections…

The basic effect of the earth's atmospheric refraction on telescope operation is the reduction of the true zenith angle to the apparent zenith angle, associated with prismatic aberrations due to the dispersion in air. If one attempts…

Astrophysics · Physics 2007-05-23 Richard J. Mathar

An approach to diffraction tomography is investigated for two-dimensional image reconstruction of objects surrounded by an arbitrarily-shaped curve of sources and receivers. Based on the integral theorem of Helmholtz and Kirchhoff, the…

Mathematical Physics · Physics 2014-11-20 G. T. Clement

360$^{\circ}$ panoramas are a rich medium, yet notoriously difficult to visualize in the 2D image plane. We explore how intelligent rotations of a spherical image may enable content-aware projection with fewer perceptible distortions.…

Computer Vision and Pattern Recognition · Computer Science 2018-08-14 Bo Xiong , Kristen Grauman

Corals are the primary habitat-building life-form on reefs that support a quarter of the species in the ocean. A coral reef ecosystem usually consists of reefs, each of which is like a tall building in any city. These reef-building corals…

Computer Vision and Pattern Recognition · Computer Science 2022-12-09 Jiageng Zhong , Ming Li , Hanqi Zhang , Jiangying Qin

Negative refraction through a triangular prism may be explained without assigning a negative refractive index to the prism by using array theory. For the case of a beam incident upon the wedge, the array theory accurately predicts the beam…

Optics · Physics 2018-03-14 Gregory A. Talalai , Timothy J. Garner , Steven J. Weiss

Accurate optical modeling is important for the design and characterisation of current and next-generation experiments studying the Cosmic Microwave Background (CMB). Geometrical Optics (GO) cannot model diffractive effects. In this work, we…

Instrumentation and Methods for Astrophysics · Physics 2020-12-15 Alexandre E. Adler , Jon E. Gudmundsson

Diffractive lenses have recently been applied to the domain of multispectral imaging in the X-ray and UV regimes where they can achieve very high resolution as compared to reflective and refractive optics. Conventionally, spectral…

Image and Video Processing · Electrical Eng. & Systems 2020-05-26 Evan Widloski , Ulas Kamaci , Farzad Kamalabadi