Computer Based General Shape Description with Polygonal Harmonics and a Roughness Index

Abstract

Description of particle shape is of wide importance in the engineering industries. Although the theory of polygonal harmonic shape analysis has been presented previously as a method for characterizing rugged particles, detailed computer implementation has not yet been described. Particle and object images have been digitized using a video camera and personal computer, and their harmonic persistences determined. The harmonic persistences are shown to relate to computer generated Fourier shapes with zero phase angle, but not to relate to Fourier coefficients describing rugged silhouettes. A relationship between the second harmonic persistence and aspect ratio is demonstrated, and it is verified that polygonal harmonics, combined with a surface roughness index, provide a general scheme for particle shape description as has been previously suggested.