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We consider curves which go around Whitney umbrella. Then we consider the geodesic and the normal curvatures, ruled surfaces generated by the normal vector and normal developable surfaces with respect to the tangent and bi-tangent vectors…

Differential Geometry · Mathematics 2025-08-22 Masayuki Hara

The problem of defining correctly geometric objects such as the curvature is a hard one in discrete geometry. In 2009, Ollivier defined a notion of curvature applicable to a wide category of measured metric spaces, in particular to graphs.…

Differential Geometry · Mathematics 2014-03-10 Benoît Loisel , Pascal Romon

Here is presented a concept of centrogeometry which can be seen as a combination of the concept of point-like observer with an idea of Poincar\'{e}'s that different geometries are principally equivalent. As it is to be shown later, all…

General Relativity and Quantum Cosmology · Physics 2009-11-09 Sergey S. Kokarev

Deflectometry as a technical approach to assessing reflective surfaces has now existed for almost 40 years. Different aspects and variations of the method have been studied in multiple theses and research articles, and reviews are also…

This paper provides an overview of modern digital geometry and topology through mathematical principles, algorithms, and measurements. It also covers recent developments in the applications of digital geometry and topology including image…

Discrete Mathematics · Computer Science 2018-07-09 Li Chen , David Coeurjolly

We investigate imaging by spherically symmetric absolute instruments that provide perfect imaging in the sense of geometrical optics. We derive a number of properties of such devices, present a general method for designing them and use this…

Optics · Physics 2014-06-16 Tomas Tyc , Lenka Herzanova , Martin Sarbort , Klaus Bering

A nested coordinate system is a reassigning of independent variables to take advantage of geometric or symmetry properties of a particular application. Polar, cylindrical and spherical coordinate systems are primary examples of such a…

General Mathematics · Mathematics 2021-01-05 Garret Sobczyk

A higher order theory of gravitation is considered which is obtained by modifying Einstein field equations. The Lagrange used to modify this in the form a polynomial in (scalar curvature) R. In this equation we have studied spherical…

General Relativity and Quantum Cosmology · Physics 2009-11-04 S. N. Pandey , B. K. Sinha

We introduce a compactification of the space of simple positive divisors on a Riemann surface, as well as a compactification of the universal family of punctured surfaces above this space. These are real manifolds with corners. We then…

Differential Geometry · Mathematics 2020-09-02 Rafe Mazzeo , Xuwen Zhu

One of the strategies to detect the pose and shape of unknown objects is their geometric modeling, consisting on fitting known geometric entities. Classical geometric modeling fits simple shapes such as spheres or cylinders, but often those…

Image and Video Processing · Electrical Eng. & Systems 2024-12-31 Joan Badia Torres , Eric Carmona , Abhijit Makhal , Omid Heidari , Alba Perez Gracia

The primary aim of this paper is to provide a simple and concrete interpretation of Cartan geometry in terms of the mathematics of idealized waywisers. Waywisers, also called hodometers, are instruments traditionally used to measure…

General Relativity and Quantum Cosmology · Physics 2015-02-17 H. F. Westman , T. G. Zlosnik

Spatial curvature is one of the fundamental cosmological parameters that is routinely constrained from observations. The forward modelling of observations, in particular of large-scale structure, often relies on large cosmological…

General Relativity and Quantum Cosmology · Physics 2026-03-10 Julian Adamek , Renan Boschetti

We investigate the geometry of holomorphic curves and complex surfaces from the perspective of singularity theory. We show that, with a suitable choice of a complex bilinear symmetric form, the families of functions and mappings that…

Differential Geometry · Mathematics 2025-12-23 Amanda Dias Falqueto , Farid Tari

Circular and radial geodesics are studied in the spacetime described by the $\gamma$ metric. Their behaviour is compared with the spherically symmetric situation, bringing out the sensitivity of the trajectories to deviations from spherical…

General Relativity and Quantum Cosmology · Physics 2009-10-31 L. Herrera , Filipe M. Paiva , N. O. Santos

A generalized Clifford manifold is proposed in which there are coordinates not only for the basis vector generators, but for each element of the Clifford group, including the identity scalar. These new quantities are physically interpreted…

General Relativity and Quantum Cosmology · Physics 2007-05-23 William M. Pezzaglia

In this paper, we give the general form of spherically symmetric Finsler metrics in $R^n$ and surprisedly find that many well-known Finsler metrics belong to this class. Then we explicitly express projective metrics of this type. The…

Differential Geometry · Mathematics 2010-06-22 Linfeng Zhou

In this paper, we study the spherical indicatrices of W-direction curves in three dimensional Euclidean space which were defined by using the unit Darboux vector field W of a Frenet curve, in [11]. We obtain the Frenet apparatus of these…

Differential Geometry · Mathematics 2015-06-15 İlkay Arslan Güven , Semra Kaya Nurkan , İpek Ağaoğlu Tor

Cylinder-shaped perfect lens deduced from the coordinate transformation method is proposed. The previously reported perfect slab lens is noticed to be a limiting form of the cylindrical lens when the inner radius approaches infinity with…

Optics · Physics 2008-09-30 Min Yan , Wei Yan , Min Qiu

Geometry of the spacetime with a spherical shell embedded in it is studied in two coordinate systems - in Kodama-Schwarzschild coordinates and in Gaussian normal coordinates. We consider transformations between the coordinate systems as in…

General Relativity and Quantum Cosmology · Physics 2016-03-23 Mikhail Z. Iofa

When matching parts of a surface to its whole, a fundamental question arises: Which points should be included in the matching process? The issue is intensified when using isometry to measure similarity, as it requires the validation of…

Computer Vision and Pattern Recognition · Computer Science 2024-10-31 Amit Bracha , Thomas Dagès , Ron Kimmel