TerrainFusion: Real-time Digital Surface Model Reconstruction based on Monocular SLAM

This paper presents an algorithm which can generate live digtial surface model (DSM) during the flight based on simultaneous localization and mapping (SLAM). We process the keyframe which is output by a monocular SLAM system to generate a local DSM, and fuse the local DSM to the global tiled DSM incrementally. During the local DSM generation, a local digital elevation model (DEM) is estimated by projecting the filtered 2D Delaunay mesh to a 3D mesh, and a local orthomosaic is obtained by projecting triangle image patches onto a 2D mesh. During the DSM fusion, both the local DEM and orthomosaic are split into tiles and fused to the global tiled DEM and orthomosaic respectively with multiband algorithm. Both the efficient DSM generation and fusion algorithms contribute to achieving a real-time reconstruction. Qualitative and quantitative experiments on a public aerial image dataset with different scenarios are performed to validate the effectiveness of the proposed method. Compared with traditional structure from motion (SfM) based approaches, the presented system is able to output both large-scale high-quality DEM and orthomosaic in real-time with low computational cost.