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We develop a sampling scheme on the sphere that permits accurate computation of the spherical harmonic transform and its inverse for signals band-limited at $L$ using only $L^2$ samples. We obtain the optimal number of samples given by the…

Information Theory · Computer Science 2014-07-25 Zubair Khalid , Rodney A. Kennedy , Jason D. McEwen

HEALPix by G\'orski et. al. (2005) is de-facto standard for Cosmic Microwave Background (CMB) data storage and analysis, and is widely used in current and upcoming CMB experiments. Almost all the datasets in Legacy Archive for Microwave…

Instrumentation and Methods for Astrophysics · Physics 2023-09-26 Andrei V. Frolov

We demonstrate a fast spin-s spherical harmonic transform algorithm, which is flexible and exact for band-limited functions. In contrast to previous work, where spin transforms are computed independently, our algorithm permits the…

Instrumentation and Methods for Astrophysics · Physics 2010-07-22 K. M. Huffenberger , B. D. Wandelt

Simulated maps of the microwave background (CMB) radiation are generally created using one of two methods: all-sky simulations use the spherical harmonic transform, while maps covering small areas approximate the sky as flat, allowing the…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-22 Mariona Giner Mascarell , Emory F. Bunn

Astronomers have come to rely on the increasing performance of computers to reduce, analyze, simulate and visualize their data. In this environment, faster computation can mean more science outcomes or the opening up of new parameter spaces…

Instrumentation and Methods for Astrophysics · Physics 2010-01-14 Benjamin R. Barsdell , David G. Barnes , Christopher J. Fluke

Deep cosmic microwave background polarization experiments allow a very precise internal reconstruction of the gravitational lensing signal in pricinple. For this aim, likelihood-based or Bayesian methods are typically necessary, where very…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-25 Martin Reinecke , Sebastian Belkner , Julien Carron

Convolutional Neural Networks (CNNs) are a cornerstone of the Deep Learning toolbox and have led to many breakthroughs in Artificial Intelligence. These networks have mostly been developed for regular Euclidean domains such as those…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-05 Nathanaël Perraudin , Michaël Defferrard , Tomasz Kacprzak , Raphael Sgier

We report the development of numerical tools for the topological analysis of sub--degree resolution, all--sky maps. Software to be released in the HEALFAST (V0.9) package defines neighbour relationships for the HEALPIX tessellation of the…

Astrophysics · Physics 2007-05-23 Benjamin D. Wandelt , Eric Hivon , Kris M. Gorski

Tomographic imaging has benefited from advances in X-ray sources, detectors and optics to enable novel observations in science, engineering and medicine. These advances have come with a dramatic increase of input data in the form of faster…

Distributed, Parallel, and Cluster Computing · Computer Science 2020-12-25 Stefano Marchesini , Anuradha Trivedi , Pablo Enfedaque , Talita Perciano , Dilworth Parkinson

It is commonplace in cosmology to analyze fields projected onto the celestial sphere, and in particular density fields that are defined by a set of points e.g. galaxies. When performing an harmonic-space analysis of such data (e.g. an…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-02 Antón Baleato Lizancos , Martin White

HEALPix -- the Hierarchical Equal Area isoLatitude Pixelization -- has become a standard in high-energy and gravitational wave astronomy. Originally developed to improve the efficiency of all-sky Fourier analyses, it is now also utilized to…

Instrumentation and Methods for Astrophysics · Physics 2022-05-18 I. Martinez-Castellanos , Leo P. Singer , E. Burns , D. Tak , Alyson Joens , Judith L. Racusin , Jeremy S. Perkins

Astronomy depends on ever increasing computing power. Processor clock-rates have plateaued, and increased performance is now appearing in the form of additional processor cores on a single chip. This poses significant challenges to the…

Instrumentation and Methods for Astrophysics · Physics 2015-05-19 Benjamin R. Barsdell , David G. Barnes , Christopher J. Fluke

3D image processing constitutes nowadays a challenging topic in many scientific fields such as medicine, computational physics and informatics. Therefore, development of suitable tools that guaranty a best treatment is a necessity.…

Numerical Analysis · Computer Science 2018-05-22 Malika Jallouli , Wafa Bel Hadj Khalifa , Anouar Ben Mabrouk , Mohamed Ali Mahjoub

High-resolution wide-angle fisheye images are becoming more and more important for robotics applications such as autonomous driving. However, using ordinary convolutional neural networks or vision transformers on this data is problematic…

Computer Vision and Pattern Recognition · Computer Science 2024-05-09 Oscar Carlsson , Jan E. Gerken , Hampus Linander , Heiner Spieß , Fredrik Ohlsson , Christoffer Petersson , Daniel Persson

We report here on a project that has developed a practical approach to processing all-sky image collections on cloud platforms, using as an exemplar application the creation of three-color Hierarchical Progressive Survey (HiPS) maps of the…

Instrumentation and Methods for Astrophysics · Physics 2024-02-08 G. Bruce Berriman , John C. Good

Recent microscopy imaging techniques allow to precisely analyze cell morphology in 3D image data. To process the vast amount of image data generated by current digitized imaging techniques, automated approaches are demanded more than ever.…

Computer Vision and Pattern Recognition · Computer Science 2020-10-26 Dennis Eschweiler , Malte Rethwisch , Simon Koppers , Johannes Stegmaier

We present $\texttt{cunusht}$, a general-purpose Python package that wraps a highly efficient CUDA implementation of the nonuniform spin-$0$ spherical harmonic transform. The method is applicable to arbitrary pixelization schemes, including…

Instrumentation and Methods for Astrophysics · Physics 2024-06-24 Sebastian Belkner , Adriaan J. Duivenvoorden , Julien Carron , Nathanael Schaeffer , Martin Reinecke

We developed a high-speed image reduction pipeline using Graphics Processing Units (GPUs) as hardware accelerators. Astronomers desire detecting EM counterpart of gravitational-wave sources as soon as possible for sharing positional…

Instrumentation and Methods for Astrophysics · Physics 2020-10-14 Masafumi Niwano , Katsuhiro L. Murata , Ryo Adachi , Sili Wang , Yutaro Tachibana , Youichi Yatsu , Nobuyuki Kawai , Takashi Shimokawabe , Ryousuke Itoh

X-ray ptychography imaging at synchrotron facilities like the Advanced Photon Source (APS) involves controlling instrument hardwares to collect a set of diffraction patterns from overlapping coherent illumination spots on extended samples,…

Instrumentation and Detectors · Physics 2022-02-10 Ke Yue , Junjing Deng , Yi Jiang , Youssef Nashed , David Vine , Stefan Vogt

We propose fast, exact and efficient algorithms for the convolution of two arbitrary functions on the sphere which speed up computations by a factor \order{\sqrt{N}} compared to present methods where $N$ is the number of pixels. No…

Astrophysics · Physics 2009-10-31 Benjamin D. Wandelt , Krzysztof M. Gorski