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We describe an algorithm that associates to each positive real number $r$ and each finite collection $C_r$ of planar pixels of size $r$ a planar piecewise linear set $S_r$ with the following additional property: if $C_r$ is the collection…

Differential Geometry · Mathematics 2015-05-27 Liviu I. Nicolaescu , Brandon Rowekamp

Motivated by the desire for a new kind of approximation, we define a type of localization called pixelation. We present how pixelation manifests in representation theory and in the study of sites and sheaves. A path category is constructed…

Category Theory · Mathematics 2026-03-27 J. Daisie Rock

We propose a novel method for semantic segmentation, the task of labeling each pixel in an image with a semantic class. Our method combines the advantages of the two main competing paradigms. Methods based on region classification offer…

Computer Vision and Pattern Recognition · Computer Science 2016-07-27 Holger Caesar , Jasper Uijlings , Vittorio Ferrari

We present a comprehensive study of the regularity of the covariance matrix of a discretized field on the sphere. In a particular situation, the rank of the matrix depends on the number of pixels, the number of spherical harmonics, the…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-12 J. D. Bilbao-Ahedo , R. B. Barreiro , D. Herranz , P. Vielva , E. Martínez-González

Blending schemes based on circles provide smooth `fair' interpolations between series of points. Here we demonstrate a simple, robust set of algorithms for performing circle blends for a range of cases. An arbitrary level of G-continuity…

Computational Geometry · Computer Science 2007-05-23 Chris Doran

We have developed in the past several algorithms with intrinsic complexity bounds for the problem of point finding in real algebraic varieties. Our aim here is to give a comprehensive presentation of the geometrical tools which are…

Algebraic Geometry · Mathematics 2009-11-23 B. Bank , M. Giusti , J. Heintz , M. Safey El Din , E. Schost

Inspired by recent use of polarimetry to study the Cosmic Microwave Background and extragalatic supernovae, a foray into the statistical properties of Stokes parameters expressed in spherical coordinates is began, allowing circular…

Instrumentation and Methods for Astrophysics · Physics 2014-11-19 Jason L. Quinn

We present an efficient method for image segmentation in the presence of strong inhomogeneities. The approach can be interpreted as a two-level clustering procedure: pixels are first grouped into superpixels via a linear least-squares…

Computer Vision and Pattern Recognition · Computer Science 2026-01-27 Jisui Huang , Andreas Alpers , Ke Chen , Na Lei

Image segmentation refers to the process to divide an image into nonoverlapping meaningful regions according to human perception, which has become a classic topic since the early ages of computer vision. A lot of research has been conducted…

Computer Vision and Pattern Recognition · Computer Science 2015-02-04 Hongyuan Zhu , Fanman Meng , Jianfei Cai , Shijian Lu

The geometric approach presented in this paper concerns the degree of polarization (DoP) of a random 3D statistical electromagnetic field. We use that a 3*3 coherency matrix can always be decomposed into an incoherent superposition of three…

The regularization of a new problem, namely the three-body problem, using 'similar' coordinate system is proposed. For this purpose we use the relation of 'similarity', which has been introduced as an equivalence relation in a previous…

Earth and Planetary Astrophysics · Physics 2011-10-31 Rodica Roman , Iharka Szucs-Csillik

The spherical harmonics $Y_{\ell m}(\theta,\varphi)$ are complex-valued functions on the surface of a sphere, and have found widespread application in physics and astronomy. Every physics students knows them from quantum mechanics and…

Classical Physics · Physics 2026-01-27 Bjoern Malte Schaefer

We introduce orthogonal ring patterns in the 2-sphere and in the hyperbolic plane, consisting of pairs of concentric circles, which generalize circle patterns. We show that their radii are described by a discrete integrable system. This is…

Metric Geometry · Mathematics 2024-10-14 Alexander I. Bobenko

This article provides an overview of the techniques related to classification of spherical and more general objects within triangulated categories, and its relationship with algebraic geometry, representation theory and symplectic geometry.…

Algebraic Geometry · Mathematics 2026-01-27 Wahei Hara , Michael Wemyss

In this paper, we develop an analytical formulation for the Slepian spatial-spectral concentration problem on the sphere for a limited colatitude-longitude spatial region on the sphere, defined as the Cartesian product of a range of…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-01 Alice P. Bates , Zubair Khalid , Rodney A. Kennedy

In this article we investigate the $N$-point min-max and the max-min polarization problems on the sphere for a large class of potentials in $\mathbb{R}^n$. We derive universal lower and upper bounds on the polarization of spherical designs…

Combinatorics · Mathematics 2022-07-20 Peter Boyvalenkov , Peter Dragnev , Douglas Hardin , Edward Saff , Maya Stoyanova

Superpixel segmentation is becoming ubiquitous in computer vision. In practice, an object can either be represented by a number of segments in finer levels of detail or included in a surrounding region at coarser levels of detail, and thus…

Computer Vision and Pattern Recognition · Computer Science 2016-05-23 Xing Wei , Qingxiong Yang , Yihong Gong , Ming-Hsuan Yang , Narendra Ahuja

Calibration of devices with different modalities is a key problem in robotic vision. Regular spatial objects, such as planes, are frequently used for this task. This paper deals with the automatic detection of ellipses in camera images, as…

Computer Vision and Pattern Recognition · Computer Science 2020-02-25 Levente Hajder , Tekla Tóth , Zoltán Pusztai

This paper presents a novel technique for camera calibration using a single view that incorporates a spherical mirror. Leveraging the distinct characteristics of the sphere's contour visible in the image and its reflections, we showcase the…

Computer Vision and Pattern Recognition · Computer Science 2025-03-18 Nissim Barzilay , Ofek Narinsky , Michael Werman

In this paper we present a differential approach to photo-polarimetric shape estimation. We propose several alternative differential constraints based on polarisation and photometric shading information and show how to express them in a…

Computer Vision and Pattern Recognition · Computer Science 2017-08-28 Silvia Tozza , William A. P. Smith , Dizhong Zhu , Ravi Ramamoorthi , Edwin R. Hancock