Grid-Centric Traffic Scenario Perception for Autonomous Driving: A Comprehensive Review

The grid-centric perception is a crucial field for mobile robot perception and navigation. Nonetheless, the grid-centric perception is less prevalent than object-centric perception as autonomous vehicles need to accurately perceive highly dynamic, large-scale traffic scenarios, and the complexity and computational costs of grid-centric perception are high. In recent years, the rapid development of deep learning techniques and hardware provides fresh insights into the evolution of grid-centric perception. The fundamental difference between grid-centric and object-centric pipeline lies in that grid-centric perception follows a geometry-first paradigm which is more robust to the open-world driving scenarios with endless long-tailed semantically unknown obstacles. Recent research demonstrates the great advantages of grid-centric perception, such as comprehensive fine-grained environmental representation, greater robustness to occlusion and irregular-shaped objects, better ground estimation, and safer planning policies. There is also a growing trend that the capacity of occupancy networks is greatly expanded to 4-D scene perception and prediction, and the latest techniques are highly related to new research topics, such as 4-D occupancy forecasting, generative artificial intelligence (GenAI), and world models in the field of autonomous driving. Given the lack of current surveys for this rapidly expanding field, we present a hierarchically structured review of grid-centric perception for autonomous vehicles. We organize previous and current knowledge of occupancy grid techniques along the main vein from 2-D bird-eye view (BEV) grids to 3-D occupancy to 4-D occupancy forecasting. We additionally summarize label-efficient occupancy learning and the role of grid-centric perception in driving systems. Finally, we present a summary of the current research trend and provide future outlooks.