Treating Point Cloud as Moving Camera Videos: A No-Reference Quality Assessment Metric

Point cloud is one of the most widely used digital representation formats for 3D contents, the visual quality of which may suffer from noise and geometric shift during the production procedure as well as compression and downsampling during the transmission process. To tackle the challenge of point cloud quality assessment (PCQA), many PCQA methods have been proposed to evaluate the visual quality levels of point clouds by assessing the rendered static 2D projections. Although such projection-based PCQA methods achieve competitive performance with the assistance of mature image quality assessment (IQA) methods, they neglect the dynamic quality-aware information, which does not fully match the fact that observers tend to perceive the point clouds through both static and dynamic views. Therefore, in this paper, we treat the point clouds as moving camera videos and explore the way of dealing with PCQA tasks via using video quality assessment (VQA) methods in a no-reference (NR) manner. First, we generate the captured videos by rotating the camera around the point clouds through four circular pathways. Then we extract both spatial and temporal quality-aware features from the selected key frames and the video clips by using trainable 2D-CNN and pre-trained 3D-CNN models respectively. Finally, the visual quality of point clouds is represented by the regressed video quality values. The experimental results reveal that the proposed method is effective for predicting the visual quality levels of the point clouds and even competitive with full-reference (FR) PCQA methods. The ablation studies further verify the rationality of the proposed framework and confirm the contributions made by the quality-aware features extracted from dynamic views.