TerrainFusion: Realtime 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 realtime 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 largescale highquality DEM and orthomosaic in realtime with low computational cost.

Directional TSDF: Modeling Surface Orientation for Coherent Meshes Realtime 3D reconstruction from RGBD sensor data plays an important role in many robotic applications, such as object modeling and mapping. The popular method of fusing depth information into a truncated signed distance function (TSDF) and applying the marching cubes algorithm for mesh extraction has severe issues with thin structures: not only does it lead to loss of accuracy, but it can generate completely wrong surfaces. To address this, we propose the directional TSDFxe2x80x94a novel representation that stores opposite surfaces separate from each other. The marching cubes algorithm is modified accordingly to retrieve a coherent mesh representation. We further increase the accuracy by using surface gradientbased ray casting for fusing new measurements. We show that our method outperforms stateoftheart TSDF reconstruction algorithms in mesh accuracy.