1 Introduction
A 3d point cloud is a collection of points representing a 3D shape, object or environment. Each point can be described by its geometric coordinates and optional associated attributes. 3D point clouds [1], [2], [3], [4] have found broad applications in manufacturing, construction, environmental monitoring, navigation, and animation. Many of these applications require high quality point clouds that faithfully reflect the geometry and perceptual attributes of the physical world. However, various distortions may be introduced during the acquisition, compression [5], transmission, storage, and rendering processes, leading to degraded perceptual quality by end users. Over the past decade, point cloud quality assessment (PCQA) has become an active field of research [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62].