ABSTRACT
Particles have various shapes depending on their manufacturing method and mechanical properties. The particle shape description or expression is classified by several criteria. In the most primitive manner, the descriptions are classified into either quantitative or qualitative method. Quantitative descriptors for the geometry of particle image can be also classified into three categories based on the scale of the inspection of form. These are macroscopic descriptor, mesoscopic descriptor, and microscopic descriptor. The descriptors derived from geometric quantities represents overall or mesoscopic feature of shape. Harmonic analysis, such as the Fourier transformation, for several images of the particle is useful. The harmonic spectrum extracted from the image function describes not only overall shape feature but microscopic shape. The property of the particle is essentially 3D. A few descriptors for 3D shape have been proposed and used in restricted fields.
