Bits-to-Photon: An End-to-End Learned Scalable Point Cloud Compression Scheme for Direct Rendering

Grunnleggende konsepter

The proposed Bits-to-Photon (B2P) method jointly designs a scalable color compression scheme and a decoder to directly generate 3D Gaussian parameters for high-quality and efficient rendering of point clouds.

Sammendrag

The paper presents a novel point cloud compression scheme called Bits-to-Photon (B2P) that addresses the challenges of high bandwidth requirement and computational complexity in volumetric video streaming. The key innovations are:

1. B2P compresses the point cloud to a compact bitstream that can be directly decoded to renderable 3D Gaussians, bridging the gap between point cloud compression, reconstruction, and rendering. This is achieved by jointly optimizing the encoder and decoder to consider both bit-rates and rendering quality.

2. B2P adapts sparse convolution for feature extraction, squeezing, conditional entropy coding, and reconstruction. It proposes a novel geometry-invariant 3D sparse convolution to address the problem of non-uniform point density in point clouds.

3. B2P introduces a novel multi-resolution coding framework for compressing the color and rendering-related information. The features at a current resolution are squeezed and entropy-coded conditioned on the features from the lower resolution to maximize redundancy reduction across resolutions. This generates a scalable bitstream with multiple levels of detail.

The proposed method significantly improves the rendering quality at similar bit-rates compared to standard and learned point cloud compression methods, while substantially reducing the decoding and rendering time. This paves the way for interactive 3D streaming applications with free viewpoints.

Statistikk

The point cloud datasets used for training and evaluation are THuman 2.0 and 8i Voxelized Full Bodies (8iVFB).
The proposed B2P method achieves over 4 dB improvements in PSNR and lower LPIPS at the same bit-rate compared to baseline methods.
B2P decoding and rendering at octree level 8 already achieves better rate-distortion performance than G-PCC at level 9.

Sitater

"Our key innovation in this paper is to design a point cloud compression scheme that compress the point cloud to a compact bitstream that can be directly decoded to renderable 3D Gaussians, bridging the gap between point cloud compression, reconstruction, and rendering."
"We adapt sparse convolution for feature extraction, squeezing, conditional entropy coding, and reconstruction. We propose a novel geometry-invariant 3D sparse convolution to address the problem of non-uniform point density in the point cloud."
"We propose a novel multi-resolution coding framework for compressing the color and rendering-related information. The features at a current resolution are squeezed and entropy-coded and reconstructed conditioned on the features from the lower resolution to maximally exploit the redundancy across resolutions."

Viktige innsikter hentet fra

Bits-to-Photon: End-to-End Learned Scalable Point Cloud Compression for Direct Rendering

by Yueyu Hu, Ra... klokken arxiv.org 09-26-2024

https://arxiv.org/pdf/2406.05915.pdf

Dypere Spørsmål

How can the proposed B2P scheme be extended to support point cloud video compression by exploiting temporal redundancy?

The proposed Bits-to-Photon (B2P) scheme can be extended to support point cloud video compression by leveraging temporal redundancy across frames in a video sequence. This can be achieved through several strategies:

Temporal Context Utilization: By incorporating features from previously decoded frames, the B2P framework can exploit the temporal coherence inherent in video data. For instance, the features extracted from a point cloud in one frame can serve as a context for encoding the next frame, allowing the model to predict and compress only the changes or differences between consecutive frames. This predictive coding can significantly reduce the amount of data that needs to be transmitted.

Hierarchical Temporal Coding: Similar to the hierarchical spatial coding used in the current B2P framework, a hierarchical approach can be applied to temporal data. By encoding the point clouds at different temporal resolutions, the system can adaptively allocate bits based on the motion and complexity of the scene. For example, static scenes may require fewer bits, while dynamic scenes with significant changes may need more detailed encoding.

Motion Estimation and Compensation: Integrating motion estimation techniques can help identify and encode the movement of objects within the point cloud. By predicting the motion vectors and compensating for them, the B2P scheme can focus on encoding the residuals, which are typically smaller in size compared to the full point cloud data.

Temporal Scalability: The B2P framework can be designed to support scalable temporal layers, where different levels of detail can be transmitted based on the available bandwidth. This would allow for real-time streaming of point cloud video, where viewers can adjust the quality based on their network conditions.

By implementing these strategies, the B2P scheme can effectively compress point cloud video data, enhancing its applicability in real-time volumetric video streaming applications.

What are the potential challenges and opportunities in developing a region-adaptive coding scheme within the B2P framework to achieve more fine-grained scalability?

Developing a region-adaptive coding scheme within the B2P framework presents both challenges and opportunities:
Challenges:

Complexity of Implementation: Implementing a region-adaptive coding scheme requires sophisticated algorithms to analyze the point cloud data and determine which regions need more detailed encoding. This adds complexity to the encoder design and may increase computational overhead.

Dynamic Scene Handling: In dynamic scenes, the regions of interest may change rapidly, making it difficult to maintain an accurate model of which areas require higher fidelity. This necessitates real-time analysis and adaptation, which can be computationally intensive.

Bit Allocation: Efficiently allocating bits among different regions while maintaining overall quality can be challenging. The system must balance the need for detail in certain areas with the constraints of available bandwidth, which may lead to trade-offs in rendering quality.

Opportunities:

Enhanced Rendering Quality: By focusing on regions that require more detail, the B2P framework can significantly improve the rendering quality of complex scenes. This targeted approach allows for better visual fidelity where it matters most, enhancing user experience in AR/VR applications.

Adaptive Streaming: A region-adaptive coding scheme can facilitate adaptive streaming, where the quality of the rendered point cloud can dynamically adjust based on the viewer's context and network conditions. This flexibility can lead to more efficient use of bandwidth and improved user satisfaction.

Improved Compression Ratios: By exploiting the spatial redundancy within the point cloud, a region-adaptive approach can achieve better compression ratios. Regions with less detail can be encoded with fewer bits, while more complex areas can receive the necessary attention, optimizing the overall data transmission.

Scalability: Implementing region-adaptive coding can enhance the scalability of the B2P framework, allowing it to cater to a wider range of devices and network conditions. This adaptability can make the system more robust and versatile for various applications.

In summary, while there are challenges in developing a region-adaptive coding scheme within the B2P framework, the potential benefits in terms of rendering quality, adaptive streaming, and compression efficiency present significant opportunities for advancement.

How can the proposed geometry-invariant 3D sparse convolution be further generalized and applied to other 3D data processing tasks beyond point cloud compression?

The proposed geometry-invariant 3D sparse convolution can be generalized and applied to various 3D data processing tasks beyond point cloud compression in several ways:

3D Object Recognition: The geometry-invariant nature of the convolution allows it to be effective in recognizing and classifying 3D objects from sparse data. By applying this convolution in neural networks designed for 3D object recognition, it can enhance the model's ability to learn features invariant to point density and distribution, improving classification accuracy.

3D Scene Understanding: In tasks such as semantic segmentation and scene parsing, the geometry-invariant 3D sparse convolution can help in accurately segmenting different objects within a scene. By maintaining the spatial relationships and structures of the 3D data, it can provide better context for understanding complex environments.

3D Reconstruction: The convolution can be utilized in 3D reconstruction tasks where the goal is to create a complete 3D model from sparse observations. By effectively handling irregular point distributions, it can improve the quality of the reconstructed surfaces and enhance the overall fidelity of the 3D model.

Robotics and Autonomous Navigation: In robotics, the geometry-invariant 3D sparse convolution can be applied to process LiDAR data for navigation and obstacle detection. Its ability to handle varying point densities can improve the robot's perception of its environment, leading to more reliable navigation and interaction with objects.

Medical Imaging: In medical imaging applications, such as analyzing 3D scans (e.g., CT or MRI), the geometry-invariant convolution can be employed to process volumetric data. This can enhance the detection of anomalies and improve the segmentation of different tissues or organs, aiding in diagnosis and treatment planning.

Augmented and Virtual Reality: The convolution can be integrated into AR/VR systems to process 3D spatial data for real-time rendering and interaction. By ensuring that the convolution is invariant to geometry, it can facilitate smoother and more realistic experiences in immersive environments.

By extending the application of geometry-invariant 3D sparse convolution to these diverse tasks, researchers and practitioners can leverage its strengths in handling irregularities in 3D data, leading to advancements in various fields that rely on 3D data processing.