用神经网络自动预测曲线细分的插入角度,统一处理欧氏、球面和双曲几何。
A Neural Tension Operator for Curve Subdivision across Constant Curvature Geometries
- 设计140K参数的神经网络,根据局部特征预测每条边的插入角。
- 在240条验证曲线上,弯曲能量和角度粗糙度显著低于传统方法。
- 适用于需要跨几何空间平滑曲线生成的研究者或图形开发者。
插值细分算法通过反复插入新顶点,将分段线性控制多边形生成光滑曲线。经典方法依赖单一全局张力参数,且在欧氏、球面和双曲几何中需分别定义。本文提出一个共享的可学习张力预测器,以单个140K参数网络替代全局参数,输入为局部内在特征和可训练几何嵌入,输出每条边的插入角度,驱动三种空间下的几何特定插入操作而无需修改架构。约束的Sigmoid输出头确保所有插入顶点在任意有限权重配置下均位于有效角度范围内。三个理论结果支撑该方法:切向安全插入的结构保证;每边自适应性的启发式动机;在显式Lipschitz约束满足的前提下,对连续可微极限曲线的条件收敛证明。在240条保留验证曲线上,所提预测器位于保真度-平滑度帕累托前沿的独立位置,弯曲能量和角度粗糙度显著低于所有固定张力及流形提升基线。黎曼流形提升保持点对点保真优势,本研究首次直接量化该优势。在分布外的ISS轨道轨迹示例中,弯曲能量降低41%,角度粗糙度降低68%,仅小幅增加豪斯多夫距离,表明预测器具有超越合成训练分布的泛化能力。
原文摘要 · Abstract (English)
Interpolatory subdivision schemes generate smooth curves from piecewise-linear control polygons by repeatedly inserting new vertices. Classical schemes rely on a single global tension parameter and typically require separate formulations in Euclidean, spherical, and hyperbolic geometries. We introduce a shared learned tension predictor that replaces the global parameter with per-edge insertion angles predicted by a single 140K-parameter network. The network takes local intrinsic features and a trainable geometry embedding as input, and the predicted angles drive geometry-specific insertion operators across all three spaces without architectural modification. A constrained sigmoid output head enforces a structural safety bound, guaranteeing that every inserted vertex lies within a valid angular range for any finite weight configuration. Three theoretical results accompany the method: a structural guarantee of tangent-safe insertions; a heuristic motivation for per-edge adaptivity; and a conditional convergence certificate for continuously differentiable limit curves, subject to an explicit Lipschitz constraint verified post hoc. On 240 held-out validation curves, the learned predictor occupies a distinct position on the fidelity--smoothness Pareto frontier, achieving markedly lower bending energy and angular roughness than all fixed-tension and manifold-lift baselines. Riemannian manifold lifts retain a pointwise-fidelity advantage, which this study quantifies directly. On the out-of-distribution ISS orbital ground-track example, bending energy falls by 41% and angular roughness by 68% with only a modest increase in Hausdorff distance, suggesting that the predictor generalises beyond its synthetic training distribution.
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