Box Guided Convolution for Pedestrian Detection

Abstract

Occlusions, scale variation and numerous false positives still represent fundamental challenges in pedestrian detection. Intuitively, different sizes of receptive fields and more attention to the visible parts are required for detecting pedestrians with various scales and occlusion levels, respectively. However, these challenges have not been addressed well by existing pedestrian detectors. This paper presents a novel convolutional network, denoted as box guided convolution network (BGCNet), to tackle these challenges simultaneously in a unified framework. In particular, we proposed a box guided convolution (BGC) that can dynamically adjust the sizes of convolution kernels guided by the predicted bounding boxes. In this way, BGCNet provides position-aware receptive fields to address the challenge of large variations of scales. In addition, for the issue of heavy occlusion, the kernel parameters of BGC are spatially localized around the salient and mostly visible key points of a pedestrian, such as the head and foot, to effectively capture high-level semantic features to help detection. Furthermore, a local maximum (LM) loss is introduced to depress false positives and highlight true positives by forcing positives, rather than negatives, as local maximums, without any additional inference burden. We evaluate BGCNet on popular pedestrian detection benchmarks, and achieve the state-of-the-art results, with the significant performance improvement on heavily occluded and small-scale pedestrians.