提出空间耦合相位到深度校准,提升三维扫描的几何一致性。
Spatially Coupled Phase-to-Depth Calibration for Fringe Projection Profilometry

- 所有像素共享统一低维映射,避免局部误差
- 在牙科数据上达到约12μm的点到面均方根误差
- 计算高效,适合实时高精度三维重建
在条纹投影轮廓术(FPP)中,深度通常通过在每个相机像素上独立拟合相位-深度关系来恢复。尽管这种逐像素校准具有高局部精度,但相邻像素即使观测同一光滑表面也可能获得显著不同的校准函数,导致空间不一致的几何结构和结构化表面伪影。本文提出一种空间耦合的相位-深度变换,所有像素共享一个单一的低维映射——全局相位标量结合未畸变参考相机网格上的仿射空间项——而非独立的逐像素拟合,可选地叠加有界且空间平滑的校正场。我们还引入原生网格配对方案,直接在参考相机网格上构建相位-深度校准对:当深度监督来自校正后的主动立体管道时,平面在立体三维空间中拟合,并沿原始光线采样回相机网格,因此相位图始终未被校正。在具有高分辨率扫描仪真值的牙科目标上,所提模型的点到面均方根误差与主动立体参考相当(约12μm),同时显著改善了逐像素多项式与有理校准的空间一致性,并将运行时映射降至每像素几个元素操作,参数存储可忽略不计。
原文摘要 · Abstract (English)
In fringe projection profilometry (FPP), depth is commonly recovered by fitting a phase-to-depth relation independently at each camera pixel. Although such pixel-wise calibration achieves high local accuracy, neighboring pixels can acquire markedly different calibration functions even when they observe the same smooth surface, producing spatially inconsistent geometry and structured surface artifacts. We propose a spatially coupled phase-depth transformation in which all pixels share a single low-dimensional mapping-global phase scalars combined with affine spatial terms on the undistorted reference-camera grid-rather than independent per-pixel fits, optionally augmented by a bounded, spatially smooth correction field. We further introduce a native-grid pairing scheme that constructs phase-depth calibration pairs directly on the reference-camera grid: when depth supervision comes from a rectified active-stereo pipeline, planes are fitted in stereo 3D and sampled back onto the camera grid along native rays, so the phase maps are never rectified. On a dental target with high-resolution scanner ground truth, the proposed model attains point-to-surface RMSE comparable to an active-stereo reference (about 12μm aggregate) while substantially improving spatial coherence over pixel-wise polynomial and rational calibration, and reduces the runtime mapping to a few element-wise operations per pixel with negligible parameter storage.
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