MM-PCQA+: Advancing Multi-Modal Learning for Point Cloud Quality Assessment

The importance of visual quality in point clouds has been significantly underlined due to the rapid rise in 3D vision applications which aim to deliver affordable and superior user experiences. Reviewing the evolution of point cloud quality assessment (PCQA), it’s observed that visual quality evaluation typically employs single-modal data, either sourced from 2D projections or the 3D point clouds. The 2D projections possess abundant texture and semantic information while they are heavily reliant on viewpoints. In contrast, 3D point clouds are more reactive to geometric distortions and viewpoint-invariant. Consequently, to maximize the benefits of both point cloud and image modalities, we present an advanced no-reference Multi-Modal Point Cloud Quality Assessment (MM-PCQA+) metric. Specifically, we divide the point clouds into sub-models to reflect local geometric distortions such as point shifting and down-sampling. Afterwards, we render the point clouds using a cube-like projection setup and sample the projections of interest using a point-visible-ratio for image feature extraction. In order to fulfill these objectives, the sub-models and projected images are encoded using point-based and image-based neural networks. Lastly, we implement symmetric cross-modal attention to amalgamate multi-modal quality-aware features. Experimental results demonstrate that our metric surpasses all state-of-the-art methods and significantly advances beyond previous no-reference PCQA methods.