Early Termination of Dyadic Region-Adaptive Hierarchical Transform for Efficient Attribute Compression of 3D Point Clouds

Thelow-complexity RAHT (Region-Adaptive Hierarchical Transform) and its corresponding Dyadic decomposition have been incorporated in the MPEG (Moving Picture Expert Group) standardization for encoding the attribute values in 3D point clouds. While significant gains were observed with the replacement of RAHT by Dyadic RAHT, the standard scheme uses only one type of decomposition for the entire point cloud. In this letter, we propose a novel adaptive scheme of switching between RAHT and Dyadic RAHT to achieve early termination of Dyadic RAHT by using 3D gradient filters. Improvements were made on the state-of-the-art scheme that uses only Dyadic RAHT transformation. The proposed method was tested on the publicly available 3D point cloud datasets. The results shows we can achieve cumulative compression gain of up to 11% over all-dyadic approach, by avoiding further decomposition in some cases.