Optimizing Initial Feature-Mapping Variables from Given Designs via Tracking

TL;DR

This paper introduces a feature-mapping framework for inverse reconstruction of topology optimization results, representing designs with geometric primitives to enable high-fidelity, gradient-based reconstruction and refinement.

Contribution

The method provides a novel differentiable feature-mapping approach using capsule-shaped primitives with exact Hessians, improving robustness and interpretability over traditional voxel-based methods.

Findings

High-fidelity reconstructions on benchmark problems

Exact Hessians accelerate convergence and robustness

Pruning and refinement improve feature efficiency

Abstract

A feature-mapping framework for inverse reconstruction of density-based topology optimization results is proposed. Unlike SIMP, whose voxelized outputs are hard to interpret or reuse, the method represents designs with high-level geometric primitives mapped to a fixed analysis grid. Capsule-shaped bars (endpoints plus radius) are used, with closed-form signed distances and smooth transition functions providing derivatives up to second order. Differentiable pseudo-densities are aggregated with smooth operators, enabling gradient-based optimization with exact Hessians. Robustness is improved through asymmetric transition functions that propagate sensitivities into void regions, a reward-only objective for initialization, and geometric safeguards against degenerate configurations. Reconstruction is performed in stages (exploration, bridging, convergence) with optional refinement that can add, remove, or merge features based on residuals and geometric criteria. Experiments on canonical SIMP benchmarks, including five-bar and cantilever layouts, show high-fidelity reconstructions using a moderate number of features. p-norm and softmax aggregation yield sharp results; pruning removes redundant features and additive refinement restores coverage. Exact Hessians accelerate convergence and improve robustness compared to quasi-Newton updates, providing a bridge from voxel-based outputs to explicit parametric models.