Weakly Supervised 3-D Building Reconstruction From Monocular Remote Sensing Images

3D building reconstruction from monocular remote sensing imagery is an important research problem that has been extensively studied for several decades. Although monocular remote sensing imagery is a more economic data source compared with the LiDAR data and multi-view imagery, its limited information results in great challenges and restricts the performance of existing monocular reconstruction methods. Moreover, the expensive cost and the limited quantity of 3D annotations also restrict the application scenes of existing methods, which are mostly based on fully-supervised learning. In our previous work, we have proposed MTBR-Net, a monocular building reconstruction method that consists of a fully-supervised multi-task network and a post-processing module for optimizing the reconstruction results. In this work, we further propose WS-MTBR-Net, a weakly-supervised building reconstruction network that uses fewer 3D annotations and achieves better performance in an end-to-end manner. Specifically, our WS-MTBR-Net fully leverages the relation between different components of a 3D building instance and the property of off-nadir images to improve the footprint segmentation boundary, based on six modified tasks and a new network structure with an improved feature warping module to support weakly-supervised learning. We also design a new training strategy via a hybrid loss function that enables utilizing the training samples with different annotation levels, i.e., complete 3D annotations, 2D footprint annotations, and image-level angle annotations. Results on BONAI Shanghai and Xi’an test datasets demonstrate that our method achieves competitive performance when using 50% fewer 3D-annotated samples, and improves the footprint segmentation F1-score by around 4% compared with current state-of-the-art.