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Many imaging problems can be formulated as mapping problems. A general mapping problem aims to obtain an optimal mapping that minimizes an energy functional subject to the given constraints. Existing methods to solve the mapping problems…

Computer Vision and Pattern Recognition · Computer Science 2022-08-16 Qiguang Chen , Zhiwen Li , Lok Ming Lui

Many genus-0 surface mapping tasks such as landmark alignment, feature matching, and image-driven registration, can be reduced (via an initial spherical conformal map) to optimizing a spherical self-homeomorphism with controlled distortion.…

Graphics · Computer Science 2026-02-05 Zhehao Xu , Lok Ming Lui

This paper presents a method to compute the {\it quasi-conformal parameterization} (QCMC) for a multiply-connected 2D domain or surface. QCMC computes a quasi-conformal map from a multiply-connected domain $S$ onto a punctured disk $D_S$…

Computational Geometry · Computer Science 2014-03-27 Kin Tat Ho , Lok Ming Lui

This paper proposes a novel method for computing bijective density-equalizing quasiconformal (DEQ) flattening maps for multiply-connected open surfaces. In conventional density-equalizing maps, shape deformations are solely driven by…

Computational Geometry · Computer Science 2024-04-01 Zhiyuan Lyu , Gary P. T. Choi , Lok Ming Lui

Surface mapping plays an important role in geometric processing. They induce both area and angular distortions. If the angular distortion is bounded, the mapping is called a {\it quasi-conformal} map. Many surface maps in our physical world…

Numerical Analysis · Mathematics 2024-07-29 W. Zeng , L. M. Lui , F. Luo , J. S. Liu , T. F. Chan , S. T. Yau , X. F. Gu

We propose a novel method for parameterizations of triangle meshes by finding an optimal quasiconformal map that minimizes an energy consisting of a relative entropy term and a quasiconformal term. By prescribing a prior probability measure…

Numerical Analysis · Mathematics 2025-11-03 Zhipeng Zhu , Lok Ming Lui

In the present paper, it was studied the boundary behavior of the so-called lower Q-homeomorphisms in the plane that are a natural generalization of the quasiconformal mappings. In particular, it was found a series of effective conditions…

Complex Variables · Mathematics 2015-02-10 Denis Kovtonyuk , Igor Petkov , Vladimir Ryazanov

In medical imaging, surface registration is extensively used for performing systematic comparisons between anatomical structures, with a prime example being the highly convoluted brain cortical surfaces. To obtain a meaningful registration,…

Computer Vision and Pattern Recognition · Computer Science 2022-08-16 Yuchen Guo , Qiguang Chen , Gary P. T. Choi , Lok Ming Lui

We consider the least-squares finite element method (lsfem) for systems of nonlinear ordinary differential equations and establish an optimal error estimate for this method when piecewise linear elements are used. The main assumptions are…

Numerical Analysis · Mathematics 2021-10-01 Matthias Chung , Justin Krueger , Honghu Liu

Registration, which aims to find an optimal 1-1 correspondence between shapes, is an important process in different research areas. Conformal mappings have been widely used to obtain a diffeomorphism between shapes that minimizes angular…

Computational Geometry · Computer Science 2012-11-13 Lok Ming Lui , Ka Chun Lam , Shing-Tung Yau , Xianfeng Gu

Over the past several decades, geometric mapping methods have been extensively developed and utilized for many practical problems in science and engineering. To assess the quality of geometric mappings, one common consideration is their…

Graphics · Computer Science 2026-04-14 Zhiyuan Lyu , Gary P. T. Choi

Evaluating the similarity of non-rigid shapes with significant partiality is a fundamental task in numerous computer vision applications. Here, we propose a novel axiomatic method to match similar regions across shapes. Matching similar…

Computer Vision and Pattern Recognition · Computer Science 2022-07-08 David Bensaïd , Amit Bracha , Ron Kimmel

Diffusion maps is a manifold learning algorithm widely used for dimensionality reduction. Using a sample from a distribution, it approximates the eigenvalues and eigenfunctions of associated Laplace-Beltrami operators. Theoretical bounds on…

Statistics Theory · Mathematics 2021-04-09 Caroline L. Wormell , Sebastian Reich

3D face registration is an important process in which a 3D face model is aligned and mapped to a template face. However, the task of 3D face registration becomes particularly challenging when dealing with partial face data, where only…

Computer Vision and Pattern Recognition · Computer Science 2024-05-17 Yuchen Guo , Hanqun Cao , Lok Ming Lui

In shape analysis, finding an optimal 1-1 correspondence between surfaces within a large class of admissible bijective mappings is of great importance. Such process is called surface registration. The difficulty lies in the fact that the…

Optimization and Control · Mathematics 2010-05-19 L. M. Lui , T. W. Wong , W. Zeng , X. F. Gu , P. M. Thompson , T. F. Chan , S. T. Yau

Optimizing deformation energies over a mesh, in two or three dimensions, is a common and critical problem in physical simulation and geometry processing. We present three new improvements to the state of the art: a barrier-aware line-search…

Optimization and Control · Mathematics 2018-02-02 Yufeng Zhu , Robert Bridson , Danny M. Kaufman

Wave equation techniques have been an integral part of geophysical imaging workflows to investigate the Earth's subsurface. Least-squares reverse time migration (LSRTM) is a linearized inversion problem that iteratively minimizes a misfit…

Computational Physics · Physics 2019-12-11 Janaki Vamaraju , Jeremy Vila , Mauricio Araya-Polo , Debanjan Datta , Mohamed Sidahmed , Mrinal Sen

We introduce computational strategies for measuring the ``size'' of the spectrum of bounded self-adjoint operators using various metrics such as the Lebesgue measure, fractal dimensions, the number of connected components (or gaps), and…

Spectral Theory · Mathematics 2024-07-31 Matthew J. Colbrook , Mark Embree , Jake Fillman

We consider a problem in eigenvalue optimization, in particular finding a local minimizer of the spectral abscissa - the value of a parameter that results in the smallest value of the largest real part of the spectrum of a matrix system.…

Optimization and Control · Mathematics 2014-11-11 Vyacheslav Kungurtsev , Wim Michiels , Moritz Diehl

Three-dimensional (3D) mappings are fundamental in various scientific and engineering applications, including computer-aided engineering (CAE), computer graphics, and medical imaging. They are typically represented and stored as…

Graphics · Computer Science 2025-09-03 Qiguang Chen , Lok Ming Lui
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