In close‐range applications, it is unclear whether optical photogrammetry is capable of accurately reconstructing submillimetre‐scale roughness. This paper presents a study of fine‐scale rock fracture roughness measurements with a careful assessment of the error. The workflow combines the techniques of structure from motion with focus stacking, using consumer‐grade equipment and free or affordable software. The approach is tested firstly with synthetic data to check the influence of the number and position of cameras, object texture and image processing using focus stacking. Secondly, the optimised workflow is used to measure a natural shale rock fracture surface. To estimate the accuracy, the results were compared with a high‐precision reference dataset provided by white‐light interferometry. The standard deviation of error in the method is 6·5 μm, and is related with morphological structures with wavelengths below 150 μm and amplitudes smaller than 10 μm.

中文翻译：

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聚焦堆叠摄影测量法用于微观粗糙度重建的方法学研究

在近距离应用中，尚不清楚光学摄影测量法是否能够准确地重建亚毫米级的粗糙度。本文介绍了对精细尺度岩石裂缝粗糙度测量的研究，并仔细评估了误差。该工作流使用消费级设备以及免费或负担得起的软件，将运动的结构技术与焦点堆叠相结合。该方法首先用合成数据进行测试，以检查照相机的数量和位置，对象纹理和使用焦点堆叠进行的图像处理的影响。其次，优化的工作流程用于测量天然页岩裂隙表面。为了估计精度，将结果与白光干涉仪提供的高精度参考数据集进行了比较。