Video-based Point Cloud Compression

Description

Video-based Point Cloud Compression (V-PCC) is a compression standard developed by 3GPP, specified in the 26.9xx series (e.g., TS 26.928), for dynamic point cloud data. A point cloud is a set of data points in a 3D coordinate system, representing the surface geometry of an object or scene, often accompanied by attributes like color and reflectance. V-PCC addresses the challenge of the enormous data size of such volumetric representations by employing a 'video-based' approach. The core idea is to project the 3D point cloud data onto 2D planes, generating geometry and texture video sequences that can be compressed using existing, highly efficient video codecs like HEVC (H.265) or VVC (H.266).

The V-PCC encoding process involves several key steps. First, the point cloud is segmented into patches—connected regions of the surface. These patches are then packed into 2D geometry and attribute (e.g., color) images. The packing algorithm aims to minimize unused space and respect patch boundaries. The geometry image encodes the depth information of each point relative to the projection plane. These generated 2D image sequences (geometry video and attribute video) are fed into a standard video encoder. Auxiliary information, such as patch metadata, projection parameters, and occupancy maps (indicating which pixels in the packed image correspond to actual points), is also generated and compressed separately, often using arithmetic coding.

On the decoder side, the process is reversed. The video bitstreams are decoded to reconstruct the 2D geometry and attribute images. Using the decoded auxiliary information, the decoder unpacks the patches and re-projects the pixels from the 2D images back into 3D space, reconstructing the original point cloud's geometry and colors. V-PCC supports both lossy and lossless compression modes and can handle dynamically changing point clouds (sequence of frames) for volumetric video. Its integration into 3GPP standards enables the streaming of this complex data over mobile networks, as the compressed bitstream can be packaged and delivered using existing multimedia delivery frameworks like DASH or MMS, making it a foundational technology for next-generation immersive media services.

Purpose & Motivation

V-PCC was standardized to enable the practical distribution and real-time communication of high-fidelity 3D volumetric content over bandwidth-constrained networks, particularly mobile networks. Prior to its development, point cloud data, especially for dynamic scenes, required prohibitively high bitrates for transmission, making applications like 6 Degrees of Freedom (6DoF) immersive video, holographic telepresence, and AR/VR sharing infeasible for mass-market consumption. Existing 3D mesh compression or generic point cloud compression methods were either not optimized for dynamic content or not sufficiently efficient for wireless transmission.

The creation of V-PCC, with work starting in Release 16, was directly motivated by the industry's move towards immersive media as a key 5G use case. 3GPP recognized that to fulfill the promise of 5G for enhanced Mobile Broadband (eMBB) and massive media services, a standardized, efficient codec for volumetric video was essential. By cleverly re-using the immense compression efficiency of decades of video coding research (through HEVC/VVC), V-PCC provides a pragmatic and highly effective solution. It solves the problem of interoperability, allowing content creators, network operators, and device manufacturers to rely on a single, well-specified compression technology for point clouds, thereby accelerating the ecosystem for immersive experiences on mobile devices.

Key Features

• Leverages existing video codecs (HEVC, VVC) for compressing 3D geometry and texture
• Supports dynamic point cloud sequences (volumetric video)
• Patch-based projection and packing of 3D data into 2D images
• Includes auxiliary information compression for metadata and occupancy maps
• Supports scalable and progressive compression modes
• Enables integration with 3GPP media delivery protocols (e.g., DASH)

Evolution Across Releases

Defining Specifications