Many three-dimensional (3D) imaging techniques, such as 3D laser scanner, stereophotography, and structured light techniques, can only capture upper half particle geometries in the camera view, and lower half particle geometries are occluded from the camera. This research aims to evaluate the accuracy of using half particle geometries to compute 3D particle shape descriptors. Computational geometry techniques are developed to compute eight commonly used particle shape descriptors automatically. Five coarse sand specimens are scanned by X-ray computed tomography and structured light to generate full 3D and half particle geometries, respectively. The convexity, diameter sphericity, and surface area sphericity computed from half particles overestimate these values computed from full 3D particles, which are corrected by statistical equations. The circularity, volume sphericity, intercept sphericity, sphere ratio sphericity, and roundness computed from half particles agreed excellently with these values computed from 3D particles. (C) 2020 Elsevier B.V. All rights reserved.