arXiv:2604.06333cs.LGcs.CV2026-04被引 8

提出新型归一化方法,让漂移模型生成更稳定且可优化的梯度场。

Drifting Fields are not Conservative

论文配图:Drifting Fields are not Conservative
图 1 · 摘自论文原文
  • 引入锐化归一化,使漂移场变为保守场,可表示为标量势的梯度
  • 新方法在非高斯核下仍保持生成质量,且实现精确平衡识别
  • 适用于希望统一生成模型与梯度流理论的研究者

漂移模型近年来因其单次前向传播生成高质量样本的能力受到关注。训练中,它们通过遵循向量值场(漂移场)学习前向映射。我们发现该过程通常不等价于优化标量损失:漂移场一般不是保守的,无法表示为任何标量势的梯度。位置依赖的归一化是导致非保守性的根源,仅高斯核是径向的例外。基于此,我们提出锐化核 $k^ ext{ extnumero}$ 和锐化归一化漂移场,使一般径向核下的场成为保守场。该向量场可表示为标量势的梯度,可用随机梯度下降直接优化。此外,该场具有核密度估计得分差的形式,并实现精确平衡可识别性。因此,锐化归一化弥合了与相关文献(如Wasserstein梯度流、去噪得分匹配)的差距,即便对非高斯核也成立。实验表明,锐化归一化在保持原漂移目标性能的同时,说明非保守灵活性并非高质量生成所必需。

原文摘要 · Abstract (English)

Drifting models have recently gained attention for generating high-quality samples in a single forward pass. During training, they learn a push-forward map by following a vector-valued field, the drift field. We ask whether this procedure is equivalent to optimizing a scalar loss and find that, in general, it is not: drift fields are not conservative and cannot be written as the gradient of any scalar potential. We identify the position-dependent normalization as the source of non-conservatism, with the Gaussian kernel as the unique radial exception. Guided by this, we introduce the sharp kernel $k^\#$ and a sharp-normalized drift field that is conservative for general radial kernels. The resulting vector field is the gradient of a scalar potential that can be optimized directly using stochastic gradient descent. Moreover, the field has the form of a score difference of kernel density estimates, and gives exact equilibrium identifiability. Thus, sharp normalization closes the gap to related literature, such as Wasserstein gradient-flows and denoising score matching, also for non-Gaussian kernels. Empirically, sharp normalization preserves the performance of the original drifting objective, suggesting that the non-conservative flexibility is not required for high-quality generation.

生成模型梯度流得分匹配非保守场

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