Flow-Based Visual Stream Compression for Event Cameras

TL;DR

This paper presents a real-time, flow-based compression method for event camera streams that significantly reduces data transmission needs while maintaining low latency and accuracy, suitable for bandwidth-constrained environments.

Contribution

The paper introduces a novel flow-based compression technique leveraging optical flow estimates for real-time event stream prediction and compression, outperforming existing methods in efficiency.

Findings

Achieves an average compression ratio of 2.81 with low temporal error.

Combines with LZMA to reach ratios up to 17.24.

Demonstrates real-time, low-latency event prediction.

Abstract

As the use of neuromorphic, event-based vision sensors expands, the need for compression of their output streams has increased. While their operational principle ensures event streams are spatially sparse, the high temporal resolution of the sensors can result in high data rates from the sensor depending on scene dynamics. For systems operating in communication-bandwidth-constrained and power-constrained environments, it is essential to compress these streams before transmitting them to a remote receiver. Therefore, we introduce a flow-based method for the real-time asynchronous compression of event streams as they are generated. This method leverages real-time optical flow estimates to predict future events without needing to transmit them, therefore, drastically reducing the amount of data transmitted. The flow-based compression introduced is evaluated using a variety of methods including spatiotemporal distance between event streams. The introduced method itself is shown to achieve an average compression ratio of 2.81 on a variety of event-camera datasets with the evaluation configuration used. That compression is achieved with a median temporal error of 0.48 ms and an average spatiotemporal event-stream distance of 3.07. When combined with LZMA compression for non-real-time applications, our method can achieve state-of-the-art average compression ratios ranging from 10.45 to 17.24. Additionally, we demonstrate that the proposed prediction algorithm is capable of performing real-time, low-latency event prediction.