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Precomputed Radiance Transfer (PRT) remains an attractive solution for real-time rendering of complex light transport effects such as glossy global illumination. After precomputation, we can relight the scene with new environment maps while…

Graphics · Computer Science 2023-07-13 Nithin Raghavan , Yan Xiao , Kai-En Lin , Tiancheng Sun , Sai Bi , Zexiang Xu , Tzu-Mao Li , Ravi Ramamoorthi

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of gamma-ray sources in the Fermi 2FGL…

Modeling information that resides on vertices of large graphs is a key problem in several real-life applications, ranging from social networks to the Internet-of-things. Signal Processing on Graphs and, in particular, graph wavelets can…

Data Structures and Algorithms · Computer Science 2016-06-14 Arlei Silva , Xuan-Hong Dang , Prithwish Basu , Ambuj K Singh , Ananthram Swami

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze…

Instrumentation and Methods for Astrophysics · Physics 2026-04-01 Krzysztof Findeisen , Ann Marie Cody , Lynne Hillenbrand

A method is derived for the quantitative analysis of signals that are composed of superpositions of isolated, time-localized "events". Here these events are taken to be well represented as rescaled and phase-rotated versions of generalized…

Methodology · Statistics 2017-04-20 J. M. Lilly

We introduce a new multiscale restoration algorithm for images with few photons counts and its use for denoising XMM data. We use a thresholding of the wavelet space so as to remove the noise contribution at each scale while preserving the…

Astrophysics · Physics 2007-05-23 H. Bourdin , E. Slezak , A. Bijaoui , M. Arnaud

Separating signals from an additive mixture may be an unnecessarily hard problem when one is only interested in specific properties of a given signal. In this work, we tackle simpler "statistical component separation" problems that focus on…

Machine Learning · Statistics 2024-03-01 Bruno Régaldo-Saint Blancard , Michael Eickenberg

The aim of this paper is to give a wavelet series representation of Linear Multifractional Stable Motion (LMSM in brief), which is more explicit than that introduced in (Ayache & Hamonier 2012). Instead of using Daubechies wavelet, which is…

Probability · Mathematics 2014-05-23 Julien Hamonier

A key goal of radio and $\gamma-$ray observations of active galactic nuclei is to characterize their time variability in order to elucidate physical processes responsible for the radiation. I describe algorithms for relevant time series…

Instrumentation and Methods for Astrophysics · Physics 2010-06-25 Jeffrey D. Scargle

Using open astronomical multifrequency databases, we constructed light curves and developed a comprehensive visualisation and sonification analysis for the blazars Mrk~501, Mrk~1501, Mrk~421, BL~Lacerta, AO~0235+164, 3C~66A, OJ~049, OJ~287,…

High Energy Astrophysical Phenomena · Physics 2026-03-11 Gustavo Magallanes-Guijón , Sergio Mendoza

We show that, in the halo model of large-scale structure formation, the difference between the Fourier and the DWT (discrete wavelet transform) power spectra provides a statistical measurement of the halos. This statistical quantity is free…

Astrophysics · Physics 2009-11-10 Ping He , Long-Long Feng , Li-Zhi Fang

Recently, machine learning methods presented a viable solution for automated classification of image-based data in various research fields and business applications. Scientists require a fast and reliable solution to be able to handle the…

Solar and Stellar Astrophysics · Physics 2020-07-07 T. Szklenár , A. Bódi , D. Tarczay-Nehéz , K. Vida , G. Marton , Gy. Mező , A. Forró , R. Szabó

This article presents an Analysis of Variance model for functional data that explicitly incorporates phase variability through a time-warping component, allowing for a unified approach to estimation and inference in presence of amplitude…

Methodology · Statistics 2013-11-11 Daniel Gervini , Patrick A. Carter

A new technique is presented for producing images from interferometric data. The method, ``smear fitting'', makes the constraints necessary for interferometric imaging double as a model, with uncertainties, of the sky brightness…

Astrophysics · Physics 2009-11-11 Robert I. Reid

Previous studies showed that hydro-climate processes are stochastic and complex systems, and it is difficult to discover the hidden patterns in the all non-stationary data and thoroughly understand the hydro-climate relationships. For the…

Applications · Statistics 2018-10-02 Jianhua Xu

Utilizing the Haar transform, we study the higher order spectral properties of mean field avalanche models, whose avalanche dynamics are described by Poisson statistics at a critical point or critical depinning transition. The Haar…

Statistical Mechanics · Physics 2007-05-23 Amit P. Mehta , Karin A. Dahmen , A. C. Mills , M. B. Weissman

Image dehazing is an ill-posed problem that has been extensively studied in the recent years. The objective performance evaluation of the dehazing methods is one of the major obstacles due to the lacking of a reference dataset. While the…

Computer Vision and Pattern Recognition · Computer Science 2020-05-08 Codruta O. Ancuti , Cosmin Ancuti , Radu Timofte

We have studied the characteristic timescales of 80 AGNs at 22, 37 and 90 GHz examining the properties of the wavelet method and comparing them to traditional Fourier-based methods commonly used in astronomy. We used the continuous wavelet…

Astrophysics · Physics 2009-11-13 T. Hovatta , H. J. Lehto , M. Tornikoski

Continuous wavelet analysis is gaining popularity in science and engineering for its ability to analyze data across spatial and scale domains simultaneously. In this study, we introduce a wavelet-based method to identify halos and assess…

Instrumentation and Methods for Astrophysics · Physics 2024-09-17 Minxing Li , Yun Wang , Ping He

Here we consider the problem of denoising features associated to complex data, modeled as signals on a graph, via a smoothness prior. This is motivated in part by settings such as single-cell RNA where the data is very high-dimensional, but…

Machine Learning · Computer Science 2023-12-12 Sam Leone , Xingzhi Sun , Michael Perlmutter , Smita Krishnaswamy