用数字孪生优化三维扫描参数,减少拍摄次数并提升精度。
Using a Digital Twin for Fringe Projection Profilometry Optimisation

- 在Blender中构建物理系统的数字孪生,模拟光栅投影过程。
- 参数优化后,拍摄图像数减少48%,测量误差降低74.0%。
- 适合需要高精度三维测量的工业质检与逆向工程场景。
光栅投影轮廓术(FPP)是一种广泛用于测量物体表面形貌和三维几何的高精度技术,需搭配优质相机与投影仪才能实现高分辨率测量。然而,在实际应用中,如何在满足现实约束的前提下选择最优参数仍具挑战。为此,本文提出一种基于Blender开源3D软件的自动化数字孪生框架,利用光线追踪环境精确模拟物理系统。通过匹配标定质量、伽马响应及标定图像,复现真实实验装置。采用张正方法[1]进行准确系统标定,获取内外参数,对高精度至关重要。利用该数字孪生,系统探索并优化关键参数,包括相位移数量、相机-投影仪间距及条纹密度。这些参数涵盖系统几何布局(如相机-投影仪位置)与算法选择(如二维相位移与解包裹方法[2])。以三个代表真实计量场景的测量标样为基准,使用对称平均切比雪夫距离(SMCD)评估重建质量。优化后将最佳参数迁移至物理系统,使每组测量所需图像数从36张降至21张(减少48%);改变条纹数量时,平均SMCD降低74.0%;仅调整相机与投影仪间距时,平均SMCD降低36.9%。
原文摘要 · Abstract (English)
Fringe projection profilometry (FPP) is a widely used technique for measuring object surface form and three-dimensional (3D) geometry, capable of delivering high-precision, high-resolution measurements when paired with suitable cameras and projectors. However, in practical deployments, identifying parameter configurations that maximise precision while satisfying real-world constraints remains challenging. To address this, we present an automated digital twin framework implemented in Blender, an open-source 3D software package that provides a ray-traced rendering environment that enables accurate simulation of physical systems. We replicated the physical setup in our digital twin by matching characterisation quality, gamma response, and characterisation images. Accurate system characterisation using Zhang's method [1], to obtain intrinsic and extrinsic parameters, is shown to be critical for achieving high precision. Using this digital twin, we then demonstrate systematic exploration and optimisation of key parameters, including phase-shift count, camera-projector spacing, and fringe density. These parameters span both system geometry (e.g. camera-projector positioning) and algorithmic choices, such as 2D phase-shifting and unwrapping methods [2]. Three measurement artefacts, representative of real world metrology scenarios, were used to benchmark the system. The symmetrical mean Chamfer distance (SMCD), computed between ground-truth and reconstructed meshes, was used to evaluate reconstruction quality. After optimisation within the digital twin, transferring the optimal parameters to the physical system reduced the number of required images per measurement by 48% (from 36 to 21). A reduction of 74.0% mean SMCD was also achieved for fringe pattern stripe count alteration. A 36.9% mean SMCD was obtained for adjusting the camera and projector spacing purely in the digital-twin.
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