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Many computational problems involve solving a linear system of equations, although only a subset of the entries of the solution are needed. In inverse problems, where the goal is to estimate unknown parameters from indirect noisy…

Numerical Analysis · Mathematics 2026-01-13 Daniela Calvetti , Nuutti Hyvönen , Ville Kolehmainen , Erkki Somersalo

We present a unified framework tackling two problems: class-specific 3D reconstruction from a single image, and generation of new 3D shape samples. These tasks have received considerable attention recently; however, most existing approaches…

Computer Vision and Pattern Recognition · Computer Science 2019-08-28 Paul Henderson , Vittorio Ferrari

We provide an algorithm for detecting the involutions leaving a surface defined by a polynomial parametrization invariant. As a consequence, the symmetry axes, symmetry planes and symmetry center of the surface, if any, can be determined…

Algebraic Geometry · Mathematics 2015-04-02 J. G. Alcázar , C. Hermoso

Recent work on the intrinsic image of humans starts to consider the visibility of incident illumination and encodes the light transfer function by spherical harmonics. In this paper, we show that such a light transfer function can be…

Computer Vision and Pattern Recognition · Computer Science 2022-03-10 Fuzhi Zhong , Rui Wang , Yuchi Huo , Hujun Bao

Aperture based scanning near field optical microscopes are important instruments to study light at the nanoscale and to understand the optical functionality of photonic nanostructures. In general, a detected image is affected by both, the…

This paper concerns time-harmonic inverse source problems with a single far-field pattern in two dimensions, where the source term is compactly supported in an a priori given inhomogeneous background medium. For convex-polygonal source…

Analysis of PDEs · Mathematics 2020-03-13 Guanghui Hu , Jingzhi Li

A face image contains geometric cues in the form of configurational information and contours that can be used to estimate 3D face shape. While it is clear that 3D reconstruction from 2D points is highly ambiguous if no further constraints…

Computer Vision and Pattern Recognition · Computer Science 2019-08-01 Anil Bas , William A. P. Smith

2D face analysis techniques, such as face landmarking, face recognition and face verification, are reasonably dependent on illumination conditions which are usually uncontrolled and unpredictable in the real world. An illumination robust…

Computer Vision and Pattern Recognition · Computer Science 2017-10-17 Wuming Zhang , Xi Zhao , Jean-Marie Morvan , Liming Chen

While invaluable for many computer vision applications, decomposing a natural image into intrinsic reflectance and shading layers represents a challenging, underdetermined inverse problem. As opposed to strict reliance on conventional…

Computer Vision and Pattern Recognition · Computer Science 2018-09-03 Qingnan Fan , Jiaolong Yang , Gang Hua , Baoquan Chen , David Wipf

In this paper, we study the problem of reproducing the world lighting from a single image of an object covered with random specular microfacets on the surface. We show that such reflectors can be interpreted as a randomized mapping from the…

Computer Vision and Pattern Recognition · Computer Science 2014-12-30 Zhengdong Zhang , Phillip Isola , Edward H. Adelson

The paper addresses the problem of energy compaction of dense 4D light fields by designing geometry-aware local graph-based transforms. Local graphs are constructed on super-rays that can be seen as a grouping of spatially and…

Computer Vision and Pattern Recognition · Computer Science 2019-10-23 Mira Rizkallah , Xin Su , Thomas Maugey , Christine Guillemot

We show how to relight a scene, depicted in a single image, such that (a) the overall shading has changed and (b) the resulting image looks like a natural image of that scene. Applications for such a procedure include generating training…

Computer Vision and Pattern Recognition · Computer Science 2021-12-10 D. A. Forsyth , Anand Bhattad , Pranav Asthana , Yuanyi Zhong , Yuxiong Wang

I propose a spatial-mode demultiplexing (SPADE) measurement scheme for the far-field imaging of spatially incoherent optical sources. For any object too small to be resolved by direct imaging under the diffraction limit, I show that SPADE…

Optics · Physics 2017-03-01 Mankei Tsang

In this paper, we propose a novel, effective and fast method to obtain a color illumination invariant and shadow-free image from a single outdoor image. Different from state-of-the-art methods for shadow-free image that either need shadow…

Computer Vision and Pattern Recognition · Computer Science 2015-01-30 Liangqiong Qu , Jiandong Tian , Zhi Han , Yandong Tang

The inverse scattering problem is of critical importance in a number of fields, including medical imaging, sonar, sensing, non-destructive evaluation, and several others. The problem of interest can vary from detecting the shape to the…

Computer Vision and Pattern Recognition · Computer Science 2024-07-16 Doga Dikbayir , Abdel Alsnayyan , Vishnu Naresh Boddeti , Balasubramaniam Shanker , Hasan Metin Aktulga

Surface reconstruction is a fundamental problem in 3D graphics. In this paper, we propose a learning-based approach for implicit surface reconstruction from raw point clouds without normals. Our method is inspired by Gauss Lemma in…

Computer Vision and Pattern Recognition · Computer Science 2022-02-22 Dong Xiao , Siyou Lin , Zuoqiang Shi , Bin Wang

The area of inverse problems in mathematics is highly interdisciplinary. In various fields of science, engineering, medicine, and industry, there arises a need to reconstruct information about unknown entities that cannot be directly…

Numerical Analysis · Mathematics 2024-09-17 Manabu Machida

The reconstruction of a 3D object or a scene is a classical inverse problem in Computer Vision. In the case of a single image this is called the Shape-from-Shading (SfS) problem and it is known to be ill-posed even in a simplified version…

Numerical Analysis · Mathematics 2016-01-28 Silvia Tozza , Maurizio Falcone

We investigate the identification of the time-dependent source term in the diffusion equation using boundary measurements. This facilitates tracing back the origins of environmental pollutants. Employing the concept of dynamic complex…

Numerical Analysis · Mathematics 2023-11-21 Lingyun Qiu , Zhongjing Wang , Hui Yu , Shenwen Yu

We consider the problem of shadowing for differential equations with grow-up. We introduce so-called nonuniform shadowing properties (in which size of the error depends on the point of the phase space) and prove for them analogs of…

Dynamical Systems · Mathematics 2014-09-25 Alexey Osipov