Scale-aware Progressive Optimization Network

Crowd counting has attracted increasing attention due to its wide application prospect. One of the most essential challenge in this domain is large scale variation, which impacts the accuracy of density estimation. To this end, we propose a scale-aware progressive optimization network (SPO-Net) for crowd counting, which trains a scale adaptive network to achieve high-quality density map estimation and overcome the variable scale dilemma in highly congested scenes. Concretely, the first phase of SPO-Net, band-pass stage, mainly concentrates on preprocessesing the input image and fusing both high-level semantic information and low-level spatial information from separated multi-layer features. And the second phase of SPO-Net, rolling guidance stage, aims to learn a scale-adapted network from multi-scale features as well as rolling training manner. For better learning local correlation of multi-size regions and reducing redundant calculations, we introduce a progressive optimization strategy. Extensive experiments on three challenging crowd counting datasets not only demonstrate the efficacy of each part in SPO-Net, but also suggest the superiority of our proposed method compared with the state-of-the-art approaches.