LOCT: A Lightweight Network Using OC-Transformer for Extracting Buildings and Roads from UAV Aerial Remote Sensing Images

Semantic segmentation for extracting buildings and roads, from unmanned aerial vehicle (UAV) remote sensing images by deep learning becomes a more efficient and convenient method than traditional manual segmentation in surveying and mapping field. In order to make the model lightweight and improve the model accuracy, A Lightweight Network Using OC-Transformer (LOCT) for Buildings and Roads from UAV Aerial Remote Sensing Images is proposed. The proposed network adopts an encoder-decoder architecture in which a Lightweight Densely Connected Network (LDCNet) is developed as the encoder. In the decoder part, the dual multi-scale context modules which consist of the Atrous Spatial Pyramid Pooling module (ASPP) and the Object Contextual Transformer module (OC-Transformer) are designed to capture more context information from feature maps of UAV remote sensing images. Between ASPP and OC-Transformer, a Feature Pyramid Network (FPN) module is used to and fuse multi-scale features extracting from ASPP. A private dataset of remote sensing images taken by UAV which contains 2431 training sets, 945 validation sets, and 475 test sets is constructed. The proposed model performs well on this dataset, with only 1.4M parameters and 5.48G floating-point operations (FLOPs), achieving an mean intersection-over-union ratio (mIoU) of 71.12%. More extensive experiments on the public LoveDA dataset and CITY-OSM dataset to further verify the effectiveness of the proposed model with excellent results on mIoU of 65.27% and 74.39%, respectively. The source code will be made available on https://github.com/GtLinyer/LOCT .