Granulometric Determination of Sedimentary Rock Particle Roundness

A number of subjective and objective methods have been proposed, and are in use, to determine the roundness of sedimentary rock particles. Roundness, which is one of three properties describing the shape of a particle, is a measure of the extent to which the corners and edges of a particle have been worn away. The objective roundness measures are mainly based on the Fourier transform. In this paper granulometric methods are proposed as alternative objective methods. In fact, we show that even a single morphological opening with a disk of adequately chosen radius can provide a roundness measure that is highly correlated with the “objective” roundness, as provided by Krumbein’s chart [5]. In addition, we propose an efficient alternative method based on a linear opening of the polar representation of the boundary of the particles considered. In our experiments, both methods compared favorably with the Fourier transform method of Diepenbroek et al. [3].