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We investigate three-dimensional surfaces where the normal vector forms a constant angle with the radius vector. These surfaces naturally extend equiangular (logarithmic) spirals in the plane.

History and Overview · Mathematics 2017-02-14 Khristo N. Boyadzhiev

We consider relative normalizations of ruled surfaces with non-vanishing Gaussian curvature $K$ in the Euclidean space $\mathbb{R} ^{3}$, which are characterized by the support functions $^{\left( \alpha \right) }q=\left \vert K\right \vert…

Differential Geometry · Mathematics 2015-11-04 Georg Stamou , Stylianos Stamatakis , Ioannis Delivos

We show that there are a finite number of possible pictures for a surface in a tetrahedron with local index $n$. Combined with previous results, this establishes that any topologically minimal surface can be transformed into one with a…

Geometric Topology · Mathematics 2013-03-28 David Bachman

The surface reconstruction problem from sets of planar parallel slices representing cross sections through 3D objects is presented. The final result of surface reconstruction is always based on the correct estimation of the structure of the…

Graphics · Computer Science 2023-01-05 Radek Svitak , Vaclav Skala

This paper presents an uncalibrated deep neural network framework for the photometric stereo problem. For training models to solve the problem, existing neural network-based methods either require exact light directions or ground-truth…

Computer Vision and Pattern Recognition · Computer Science 2021-04-20 Berk Kaya , Suryansh Kumar , Carlos Oliveira , Vittorio Ferrari , Luc Van Gool

We show that for a certain family of integrable reversible transformations, the curves of periodic points of a general transformation cross the level curves of its integrals. This leads to the divergence of the normal form for a general…

Complex Variables · Mathematics 2009-09-25 Xianghong Gong

Neural implicit reconstruction via volume rendering has demonstrated its effectiveness in recovering dense 3D surfaces. However, it is non-trivial to simultaneously recover meticulous geometry and preserve smoothness across regions with…

Computer Vision and Pattern Recognition · Computer Science 2025-04-09 Ziyu Tang , Weicai Ye , Yifan Wang , Di Huang , Hujun Bao , Tong He , Guofeng Zhang

Regularization in convolutional neural networks (CNNs) is usually addressed with dropout layers. However, dropout is sometimes detrimental in the convolutional part of a CNN as it simply sets to zero a percentage of pixels in the feature…

Image and Video Processing · Electrical Eng. & Systems 2021-08-29 Juan P. Vigueras-Guillén , Joan Lasenby , Frank Seeliger

Extracting planes from a 3D scene is useful for downstream tasks in robotics and augmented reality. In this paper we tackle the problem of estimating the planar surfaces in a scene from posed images. Our first finding is that a surprisingly…

Computer Vision and Pattern Recognition · Computer Science 2024-06-14 Jamie Watson , Filippo Aleotti , Mohamed Sayed , Zawar Qureshi , Oisin Mac Aodha , Gabriel Brostow , Michael Firman , Sara Vicente

This work introduces a new fitting formalism for isophotes which enables more accurate modelling of galaxies with non-elliptical shapes, such as disk galaxies viewed edge-on or galaxies with X-shaped/peanut bulges. Within this scheme, the…

Astrophysics of Galaxies · Physics 2015-09-23 Bogdan C. Ciambur

This paper is concerned with the inverse problem of reconstructing small and local perturbations of a planar surface using the field interaction between a known plasmonic particle and the planar surface. The aim is to perform a…

Analysis of PDEs · Mathematics 2018-11-21 Habib Ammari , Doo Sung Choi , Sanghyeon Yu

We consider practical aspects of reconstructing planar curves with prescribed Euclidean or affine curvatures. These curvatures are invariant under the special Euclidean group and the equi-affine groups, respectively, and play an important…

Differential Geometry · Mathematics 2024-04-02 Jose Agudelo , Brooke Dippold , Ian Klein , Alex Kokot , Eric Geiger , Irina Kogan

In this work, we study the perception problem for sampled surfaces (possibly with boundary) using tools from computational topology, specifically, how to identify their underlying topology starting from point-cloud samples in space, such as…

Computational Geometry · Computer Science 2024-10-17 Franco Coltraro , Jaume Amorós , Maria Alberich-Carramiñana , Carme Torras

Normalizing flows are a powerful technique for obtaining reparameterizable samples from complex multimodal distributions. Unfortunately current approaches fall short when the underlying space has a non trivial topology, and are only…

Machine Learning · Statistics 2020-06-12 Luca Falorsi , Patrick Forré

Phase retrieval is a nonlinear inverse problem that arises in a wide range of imaging modalities, from electron microscopy to Fourier ptychography. In particular, the reconstruction is facilitated when the sensing matrix is i.i.d. random,…

Normal multi-scale transform [4] is a nonlinear multi-scale transform for representing geometric objects that has been recently investigated [1, 7, 10]. The restrictive role of the exact order of polynomial reproduction $P_e$ of the…

Numerical Analysis · Mathematics 2013-11-19 Stanislav Harizanov

We introduce circular evolutes and involutes of framed curves in the Euclidean space. Circular evolutes of framed curves stem from the curvature circles of Bishop directions and singular value sets of normal surfaces of Bishop directions.…

Differential Geometry · Mathematics 2021-03-15 Shun'ichi Honda , Masatomo Takahashi

We use global bifurcation techniques to establish the existence of arbitrarily many geometrically distinct nonplanar embedded smooth minimal 2-spheres in sufficiently elongated 3-dimensional ellipsoids of revolution. More precisely, we…

Differential Geometry · Mathematics 2025-11-05 Renato G. Bettiol , Paolo Piccione

We introduce a system and methods for the three-dimensional measurement of extended specular surfaces with high surface normal variations. Our system consists only of a mobile hand held device and exploits screen and front camera for…

Computer Vision and Pattern Recognition · Computer Science 2019-07-26 Florian Willomitzer , Chia-Kai Yeh , Vikas Gupta , William Spies , Florian Schiffers , Marc Walton , Oliver Cossairt

We combine two-dimensional freeform reflector design with a scattering surface modelled using microfacets, i.e., small specular surfaces representing surface roughness. The model results in a convolution integral for the scattered light…

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