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Interferometric Synthetic Aperture Radar (InSAR) Imaging methods are usually based on algorithms of match-filtering type, without considering the scene's characteristic, which causes limited imaging quality. Besides, post-processing steps…

Signal Processing · Electrical Eng. & Systems 2022-10-07 Xu Zhan , Xiaoling Zhang , Shunjun Wei , Jun Shi

Aims: To propose a method for the polarimetric calibration of large astronomical mirrors that does not require use of special optical devices nor knowledge of the exact polarization properties of the calibration target. Methods: We study…

Instrumentation and Methods for Astrophysics · Physics 2015-11-11 A. Lopez Ariste

Camera calibration is an essential first step in setting up 3D Computer Vision systems. Commonly used parametric camera models are limited to a few degrees of freedom and thus often do not optimally fit to complex real lens distortion. In…

Computer Vision and Pattern Recognition · Computer Science 2020-06-24 Thomas Schöps , Viktor Larsson , Marc Pollefeys , Torsten Sattler

Many Multi-View-Stereo algorithms extract a 3D mesh model of a scene, after fusing depth maps into a volumetric representation of the space. Due to the limited scalability of such representations, the estimated model does not capture fine…

Computer Vision and Pattern Recognition · Computer Science 2019-05-23 Andrea Romanoni , Matteo Matteucci

Camera calibration is a crucial prerequisite in many applications of computer vision. In this paper, a new, geometry-based camera calibration technique is proposed, which resolves two main issues associated with the widely used Zhang's…

Computer Vision and Pattern Recognition · Computer Science 2019-08-20 Jen-Hui Chuang , Chih-Hui Ho , Ardian Umam , HsinYi Chen , Mu-Tien Lu , Jenq-Neng Hwang , Tai-An Chen

Calibration precision is currently a limiting systematic in 21 cm cosmology experiments. While there are innumerable calibration approaches, most can be categorized as either `sky-based,' relying on an extremely accurate model of…

Instrumentation and Methods for Astrophysics · Physics 2021-03-17 Ruby Byrne , Miguel F. Morales , Bryna Hazelton , Michael Wilensky

Performing reliable measurements in optical metrology, such as those needed in ellipsometry, requires a calibrated source and detector, or a well-characterized reference sample. We present a novel interferometric technique to perform…

This paper proposes a new preconditioning scheme for a linear system with a saddle-point structure arising from a hybrid approximation scheme on the sphere, an approximation scheme that combines (local) spherical radial basis functions and…

Numerical Analysis · Mathematics 2010-09-23 Q. T. Le Gia , Ian H. Sloan , Andrew J. Wathen

Vision-based motion estimation and 3D reconstruction, which have numerous applications (e.g., autonomous driving, navigation systems for airborne devices and augmented reality) are receiving significant research attention. To increase the…

Computer Vision and Pattern Recognition · Computer Science 2018-10-30 Vladyslav Usenko , Nikolaus Demmel , Daniel Cremers

We give an explicit estimate of the area of a closed surface by the diameter and a lower bound of curvature. This is better than Calabi-Cao's estimate for a nonnegatively curved two-sphere.

Differential Geometry · Mathematics 2014-08-01 Takashi Shioya

The recent development of calibration algorithms has been driven into two major directions: (1) an increasing accuracy of mathematical approaches and (2) an increasing flexibility in usage by reducing the dependency on calibration objects.…

Robotics · Computer Science 2020-04-28 Bjarne Grossmann , Volker Krueger

We introduce a new method for testing departure from isotropy of points on a sphere based on an enhanced form of the two-point correlation function that we named 2pt+. This method uses information from the two extra variables that define…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-22 M. Ave , L. Cazon , J. Cronin , J. R. T. de Mello Neto , A. V. Olinto , V. Pavlidou , P. Privitera , B. B. Siffert , F. Schmidt , T. Venters

Variational regularization of ill-posed inverse problems is based on minimizing the sum of a data fidelity term and a regularization term. The balance between them is tuned using a positive regularization parameter, whose automatic choice…

Numerical Analysis · Mathematics 2025-11-12 Markus Juvonen , Bjørn Jensen , Ilmari Pohjola , Yiqiu Dong , Samuli Siltanen

We present a method of extrinsic calibration for a system of multiple inertial measurement units (IMUs) that estimates the relative pose of each IMU on a rigid body using only measurements from the IMUs themselves, without the need to…

Robotics · Computer Science 2022-05-31 Jongwon Lee , David Hanley , Timothy Bretl

Response calibration is the process of inferring how much the measured data depend on the signal one is interested in. It is essential for any quantitative signal estimation on the basis of the data. Here, we investigate self-calibration…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 Torsten A. Enßlin , Henrik Junklewitz , Lars Winderling , Maksim Greiner , Marco Selig

Calibration of multi-camera systems, i.e. determining the relative poses between the cameras, is a prerequisite for many tasks in computer vision and robotics. Camera calibration is typically achieved using offline methods that use…

Computer Vision and Pattern Recognition · Computer Science 2022-09-16 Bastian Pätzold , Simon Bultmann , Sven Behnke

Circular markers are planar markers which offer great performances for detection and pose estimation. For an uncalibrated camera with an unknown focal length, at least the images of at least two coplanar circles are generally required to…

Computer Vision and Pattern Recognition · Computer Science 2018-04-16 Mariyanayagam Damien , Gurdjos Pierre , Chambon Sylvie , Brunet Florent , Charvillat Vincent

The 2-sets convex feasibility problem aims at finding a point in the nonempty intersection of two closed convex sets $A$ and $B$ in a Hilbert space $X$. The method of alternating projections is the simplest iterative procedure for finding a…

Optimization and Control · Mathematics 2020-06-29 Carlo A. De Bernardi , Enrico Miglierina

Many robotics and mapping systems contain multiple sensors to perceive the environment. Extrinsic parameter calibration, the identification of the position and rotation transform between the frames of the different sensors, is critical to…

Robotics · Computer Science 2019-08-27 Hongyu Chen , Sören Schwertfeger

This paper investigates calibration of sensor arrays in the radio astronomy context. Current and future radio telescopes require computationally efficient algorithms to overcome the new technical challenges as large collecting area, wide…

Applications · Statistics 2018-07-31 Virginie Ollier , Mohammed Nabil El Korso , André Ferrari , Rémy Boyer , Pascal Larzabal