Irregular Shape Symmetry Analysis: Theory and Application to Quantitative Galaxy Classification

This paper presents a set of imperfectly symmetric measures based on a series of geometric transformation operations for quantitatively measuring the “amount” of symmetry of arbitrary shapes. The definitions of both bilateral symmetricity and rotational symmetricity give new insight into analyzing the geometrical property of a shape and enable characterizing arbitrary shapes in a new way. We developed a set of criteria for quantitative galaxy classification using our proposed irregular shape symmetry measures. Our study has demonstrated the effectiveness of the proposed method for the characterization of the shape of the celestial bodies. The concepts described in the paper are applicable to many fields, such as mathematics, artificial intelligence, digital image processing, robotics, biomedicine, etc.