Hierarchical Context Network for Airborne Image Segmentation

Most of the recent methods focus on capturing contextual information by measuring relations (e.g., feature similarity) between each pixel and all the others for airborne image segmentation. Nevertheless, these methods have difficulty in handling confusing objects with a partially similar appearance. In this article, we attempt to simultaneously explore pixel-to-pixel (P2P) and pixel-to-object (P2O) relations to learn contextual information. For this purpose, a hierarchical context network (HCNet) is proposed. It consists of a P2P subnetwork and a P2O subnetwork. The P2P subnetwork learns the P2P relation (detail-grained context) for better preservation of the details (e.g., boundary) of the objects. Meanwhile, the P2O subnetwork models the P2O relation (semantic-grained context), aiming at improving the intraobject semantic consistency. When inferring the segmentation results, outputs of these two subnetworks are aggregated to obtain the hierarchical contextual information. Experimental results demonstrate that the proposed model achieves competitive performance on three challenging benchmarks.