Unmanned Aerial Vehicles (UAVs) require the ability to robustly perceive surrounding scenes for autonomous navigation. The semantic reconstruction of the scene is a truly functional understanding of the environment. However, high-performance computing is generally not available on most UAVs, so a lightweight real-time semantic reconstruction method is necessary. Existing methods rely on GPU, and it is difficult to achieve real-time semantic reconstruction on CPU. To solve the problem, an indoor dense semantic Simultaneous Localization and Mapping (SLAM) method using CPU computing is proposed in this paper, named CDSFusion. The CDSFusion is the first system integrating RGBD-based Visual-Inertial Odometry (VIO), semantic segmentation and 3D reconstruction in real-time on a CPU. In our VIO method, the depth information is introduced to improve the accuracy of pose estimation, and FAST features are used for faster tracking. In our semantic reconstruction method, the PSPNet (Pyramid Scene Parsing Network) pre-trained model is optimized to provide the semantic information in real-time on the CPU, and the semantic point clouds are fused using Voxblox. The experimental results demonstrate that camera tracking is accelerated without loss of accuracy in our VIO, and a 3D semantic map is reconstructed in real-time, which is comparable to one generated by the GPU-dependent method.

Unmanned aerial vehicles (UAVs) are extensively employed for urban image captures and the reconstruction of large-scale 3D models due to their affordability and versatility. However, most commercial flight software lack support for the adaptive capture of multi-view images. Furthermore, the limited performance and battery capacity of a single UAV hinder efficient image capturing of large-scale scenes. To address these challenges, this paper presents a novel method for multi-UAV continuous trajectory planning aimed at the image captures and reconstructions of a scene. Our primary contribution lies in the development of a path planning framework rooted in task and search principles. Within this framework, we initially ascertain optimal task locations for capturing images by assessing scene reconstructability, thereby enhancing the overall quality of reconstructions. Furthermore, we curtail energy costs of trajectories by allocating task sequences, characterized by minimal corners and lengths, among multiple UAVs. Ultimately, we integrate considerations of energy costs, safety, and reconstructability into a unified optimization process, facilitating the search for optimal paths for multiple UAVs. Empirical evaluations demonstrate the efficacy of our approach in facilitating collaborative full-scene image captures by multiple UAVs, achieving low energy costs while attaining high-quality 3D reconstructions.

Real-time 3D reconstruction combined with MAVs has garnered significant attention in a variety of fields, including building maintenance, geological exploration, emergency rescue, and cultural heritage protection. While MAVs possess the advantages of speed and lightness, they also exhibit strong image blur and limited computational resources. To address these limitations, this paper presents a novel approach for onboard, depth-only, real-time 3D reconstruction capable of accommodating fast-moving MAVs. Our primary contribution is a dense SLAM system that combines surface hierarchical sparse representation and particle swarm pose optimization. Our system enables the robust tracking of high-speed camera motion and facilitates scaling to large scenes without being constrained by GPU memory resources. Our robust camera tracking framework is capable of accommodating fast camera motions and varying environments solely by relying on depth images. Furthermore, by integrating path planning methods, we explore the capabilities of MAV autonomous mapping in unknown environments with restricted lighting. Our efficient reconstruction system is capable of generating highly dense point clouds with resolutions ranging from 2 mm to 8 mm on surfaces of different complexities at rates approaching 30 Hz, fully onboard a MAV. We evaluate the performance of our method on both datasets and real-world platforms and demonstrate its superior accuracy and efficiency compared to existing methods.