A novel method for high dynamic range optical measurement with single shot by multi-view stereo

Abstract

Due to the limited dynamic range of cameras, reconstruction tasks on high dynamic range surfaces often exhibit overexposed and underexposed regions in the captured images, compromising measurement accuracy and completeness. Existing high dynamic range measurement techniques perform 3D reconstruction directly using image intensity or multi-exposure fusion methods. These techniques cannot simultaneously meet the requirements of single-shot measurement, high precision, high completeness, and ease of use. In this article, we propose a novel measurement method with single shot to address these challenges. Different from existing methods, a multi-view stereo pipeline is proposed to fully utilize the properly exposed areas of different views. By multi-view matching based on photometric and geometric consistency, the depth and normal vector for each pixel in every view will be obtained. The depth and normal vector can be combined into a spatial slanted plane, initializing the first-order shape function parameters. A multi-view digital speckle correlation method is proposed to optimize the plane parameters. Finally, the plane parameters are integrated to produce the depth map fusion. A four-camera measurement system with a photolithographic speckle projection module is developed for experimental validation. Extensive quantitative and qualitative experiments demonstrate that the proposed method achieves the measurement accuracy of 0.04–0.07 mm, meeting the requirements of industrial applications.