Particles are frequently analyzed by microscopy or image analyzers. The two-dimensionally (2D) observed size and shape characteristics of such particles differ from the three-dimensional (3D) characteristics, due to the stereological difference between 2D and 3D assessment. In this study, a 2D-3D conversion method for estimating 3D particle size and shape characteristics from measurable 2D characteristics was modified, for better estimation, by the use of spherical harmonic-based principal component analysis; and enhanced for applicability to 3D estimations based on particle projections or cross-sections. Experimental validation showed that seven 3D indices (sphericity, long/middle axis ratio, long/short axis ratio, volume, surface area, equivalent diameter, and long axis length) were successfully estimated from measurable 2D indices. In addition, discrete element simulations were conducted on original 3D particles and 3D particles estimated based on 2D particle projections, and the results showed successful reproduction of the repose angle in the estimated 3D particle shapes.(c) 2022 Elsevier B.V. All rights reserved.
