Abstract:Many algorithms on meshes require the minimization of composite objectives, i.e., energies that are compositions of simpler parts. Canonical examples include mesh parameterization and deformation. We propose a second order optimization approach that exploits this composite structure to efficiently converge to a local minimum.Our main observation is that a convex-concave decomposition of the energy constituents is simple and readily available in many cases of practical relevance in graphics. We utilize such con… Show more
“…Claici et al [2017] proposed a preconditioner for fast minimization of distortion energies. Shtengel et al [2017] applied the idea of majorizationminimization [Lange 2004] to iteratively update and minimize a convex majorizer of the target energy in geometric optimization. Zhu et al [2018] proposed a fast solver for distortion energy minimization, using a blended quadratic energy proxy together with improved line-search strategy and termination criteria.…”
Section: Related Workmentioning
confidence: 99%
“…Such tasks are often formulated as unconstrained optimization, where the target function penalizes the violation of certain conditions so that they are satisfied as much as possible by the solution. It has been an active research topic to develop fast numerical solvers for such problems, with various methods proposed in the past [Sorkine and Alexa 2007;Liu et al 2008;Bouaziz et al 2012;Wang 2015;Kovalsky et al 2016;Liu et al 2017;Shtengel et al 2017;Rabinovich et al 2017].…”
“…Claici et al [2017] proposed a preconditioner for fast minimization of distortion energies. Shtengel et al [2017] applied the idea of majorizationminimization [Lange 2004] to iteratively update and minimize a convex majorizer of the target energy in geometric optimization. Zhu et al [2018] proposed a fast solver for distortion energy minimization, using a blended quadratic energy proxy together with improved line-search strategy and termination criteria.…”
Section: Related Workmentioning
confidence: 99%
“…Such tasks are often formulated as unconstrained optimization, where the target function penalizes the violation of certain conditions so that they are satisfied as much as possible by the solution. It has been an active research topic to develop fast numerical solvers for such problems, with various methods proposed in the past [Sorkine and Alexa 2007;Liu et al 2008;Bouaziz et al 2012;Wang 2015;Kovalsky et al 2016;Liu et al 2017;Shtengel et al 2017;Rabinovich et al 2017].…”
“…[2017] presented a scalable approach for optimizing flip-preventing energies, using a reweighted proxy function in each iteration. Shtengel et al [2017] derived convex majorizers of composite energies via convex-concave decompositions, which are repeatedly updated and minimized to obtain a minimum of the target energy.…”
Many computer graphics problems require computing geometric shapes subject to certain constraints. This often results in non-linear and non-convex optimization problems with globally coupled variables, which pose great challenge for interactive applications. Local-global solvers developed in recent years can quickly compute an approximate solution to such problems, making them an attractive choice for applications that prioritize efficiency over accuracy. However, these solvers suffer from lower convergence rate, and may take a long time to compute an accurate result. In this paper, we propose a simple and effective technique to accelerate the convergence of such solvers. By treating each local-global step as a fixed-point iteration, we apply Anderson acceleration, a well-established technique for fixed-point solvers, to speed up the convergence of a local-global solver. To address the stability issue of classical Anderson acceleration, we propose a simple strategy to guarantee the decrease of target energy and ensure its global convergence. In addition, we analyze the connection between Anderson acceleration and quasi-Newton methods, and show that the canonical choice of its mixing parameter is suitable for accelerating local-global solvers. Moreover, our technique is effective beyond classical local-global solvers, and can be applied to iterative methods with a common structure. We evaluate the performance of our technique on a variety of geometry optimization and physics simulation problems. Our approach significantly reduces the number of iterations required to compute an accurate result, with only a slight increase of computational cost per iteration. Its simplicity and effectiveness makes it a promising tool for accelerating existing algorithms as well as designing efficient new algorithms.
“…Further timing comparisons to composite majorization (CM) [SPSH∗17] on selected group B models are in Table . Here, our method also possesses a significant speedup, and can process large models with millions of triangles in several seconds.…”
We present a fast algorithm for low‐distortion locally injective harmonic mappings of genus 0 triangle meshes with and without cone singularities. The algorithm consists of two portions, a linear subspace analysis and construction, and a nonlinear non‐convex optimization for determination of a mapping within the reduced subspace. The subspace is the space of solutions to the Harmonic Global Parametrization (HGP) linear system [BCW17], and only vertex positions near cones are utilized, decoupling the variable count from the mesh density. A key insight shows how to construct the linear subspace at a cost comparable to that of a linear solve, extracting a very small set of elements from the inverse of the matrix without explicitly calculating it. With a variable count on the order of the number of cones, a tangential alternating projection method [HCW17] and a subsequent Newton optimization [CW17] are used to quickly find a low‐distortion locally injective mapping. This mapping determination is typically much faster than the subspace construction. Experiments demonstrating its speed and efficacy are shown, and we find it to be an order of magnitude faster than HGP and other alternatives.
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