FastOcc: Accelerating 3D Occupancy Prediction by Fusing the 2D Bird's-Eye View and Perspective View

TL;DR

FastOcc is a novel method that significantly accelerates 3D occupancy prediction in autonomous driving by replacing heavy 3D convolutions with a lightweight 2D BEV approach, maintaining high accuracy and achieving state-of-the-art results.

Contribution

The paper introduces a residual-like architecture that replaces 3D convolutions with lightweight 2D BEV convolutions and feature interpolation, boosting inference speed without sacrificing accuracy.

Findings

FastOcc achieves state-of-the-art results on Occ3D-nuScenes.

Inference speed is significantly improved by the new architecture.

Maintains high accuracy comparable to existing methods.

Abstract

In autonomous driving, 3D occupancy prediction outputs voxel-wise status and semantic labels for more comprehensive understandings of 3D scenes compared with traditional perception tasks, such as 3D object detection and bird's-eye view (BEV) semantic segmentation. Recent researchers have extensively explored various aspects of this task, including view transformation techniques, ground-truth label generation, and elaborate network design, aiming to achieve superior performance. However, the inference speed, crucial for running on an autonomous vehicle, is neglected. To this end, a new method, dubbed FastOcc, is proposed. By carefully analyzing the network effect and latency from four parts, including the input image resolution, image backbone, view transformation, and occupancy prediction head, it is found that the occupancy prediction head holds considerable potential for accelerating the model while keeping its accuracy. Targeted at improving this component, the time-consuming 3D convolution network is replaced with a novel residual-like architecture, where features are mainly digested by a lightweight 2D BEV convolution network and compensated by integrating the 3D voxel features interpolated from the original image features. Experiments on the Occ3D-nuScenes benchmark demonstrate that our FastOcc achieves state-of-the-art results with a fast inference speed.