  Semantic segmentation necessitates approaches that learn high-level
characteristics while dealing with enormous amounts of data. Convolutional
neural networks (CNNs) can learn unique and adaptive features to achieve this
aim. However, due to the large size and high spatial resolution of remote
sensing images, these networks cannot analyze an entire scene efficiently.
Recently, deep transformers have proven their capability to record global
interactions between different objects in the image. In this paper, we propose
a new segmentation model that combines convolutional neural networks with
transformers, and show that this mixture of local and global feature extraction
techniques provides significant advantages in remote sensing segmentation. In
addition, the proposed model includes two fusion layers that are designed to
represent multi-modal inputs and output of the network efficiently. The input
fusion layer extracts feature maps summarizing the relationship between image
content and elevation maps (DSM). The output fusion layer uses a novel
multi-task segmentation strategy where class labels are identified using
class-specific feature extraction layers and loss functions. Finally, a
fast-marching method is used to convert all unidentified class labels to their
closest known neighbors. Our results demonstrate that the proposed methodology
improves segmentation accuracy compared to state-of-the-art techniques.
