AbstractIt has been shown that the projected area of a rotating fineparticle can be used to construct a signature waveform which is descriptive of some aspects of the three‐dimensional morphology of a fineparticle. If the fineparticle is rotated systematically about two mutually independent axes, through two sets of 90 degrees rotations, the signature waveform can be related to the surface area of the convex hull. It could be that the convex hull of a fineparticle is related to its fluid dynamic behaviour and its ability to modify the effective viscosity of a fluid in its suspension. This type of significance of different types of Cauchy signature waveforms are discussed. The concept of three‐dimensional signature waveforms is extended to cover the structural shape waveform and the fractal waveforms which, respectively, describe the spatial structure and the ruggedness of a fineparticle profile. The possible utilization of all three types of waveforms to describe in a complete manner the three‐dimensional structure of a rugged fineparticle is disc