Global-local Feature Aggregation for Event-based Object Detection on EventKITTI

Event sequence conveys asynchronous pixel-wise visual information in a low power and high temporal resolution manner, which enables more robust perception under challenging conditions, e.g., fast motion. Two main factors limit the development of event-based object detection in traffic scenes: lack of high-quality datasets and effective event-based algorithms. To solve the first problem, we propose a simulated event-based detection dataset named EventKITTI, which incorporates the novel event modality information into a mixed two-level (i.e. object-level and video-level) detection dataset under traffic scenarios. EventKITTI possesses the high-quality event stream and the largest number of categories at microsecond temporal resolution and 1242×375 spatial resolution, exceeding existing datasets. As for the second problem, existing algorithms rely on CNN-based, spiking or graph architectures to capture local features of moving objects, leading to poor performance in objects with incomplete contours. Hence, we propose event-based object detectors named GFA-Net and CGFA-Net. To enhance the global-local learning ability in the spatial dimension, GFA-Net introduces transformer with edge-based position encoding and multi-scale feature fusion to detect objects on static frame. Furthermore, CGFA-Net optimizes edge-based position encoding with close-loop learning based on previous detected heatmap, which aggregates temporal global features across event frames. The proposed event-based object detectors achieve the best speed-accuracy trade-off on EventKITTI, approaching an 81.3% MAP at 33.0 FPS on object-level detection dataset and a 64.5% MAP at 30.3 FPS on video-level detection dataset.