Panoramic RGB-D cameras enable high-quality 3D scene reconstruction but require manual viewpoint selection and physical camera transportation, making the process time-consuming and tedious—especially for novice users. Key challenges include ensuring sufficient feature overlap between camera views and planning collision-free paths. We propose a fully autonomous scan planner that generates efficient and collision-free tours with adequate viewpoint overlap to address these issues. Experiments in both synthetic and real-world environments show that our method achieves up to 99% scan coverage and is up to three times faster than state-of-the-art view planning approaches.

We present an efficient and scalable learning-based autonomous exploration system for mobile robots navi-gating unknown indoor environments. Our system incorporates three network models trained to identify the frontier region (FR), to evaluate the detected FR regions based on their proximity to the robot (A*-Net), and to measure the coverage reward at the FR regions (Viz-Net). Our method employs an active window of the map that moves along with the robot, offering scalable exploration capabilities while maintaining a high rate of exploration coverage owing to the two exploratory measures utilized by A*-Net (proximity) and Viz-Net (coverage). Consequently, Our system completes over 99% coverage in a large-scale benchmarking world, scaling up to 135m × +80m. In contrast, other state-of-the-art approaches completed only less than 40% of the same world with a 30% slower exploration speed than ours.

We propose a fully autonomous system for mobile robot exploration in unknown environments. Our system employs a novel frontier detection algorithm based on the fast front propagation (FFP) technique and uses parallel path planning to reach the detected front regions. Given an occupancy grid map in 2D, possibly updated online, our algorithm can find all the frontier points that can allow mobile robots to visit unexplored regions to maximize the exploratory coverage. Our FFP method is six~seven times faster than the state-of-the-art wavefront frontier detection algorithm in terms of finding frontier points without compromising the detection accuracy. The speedup can be further accelerated by simplifying the map without degrading the detection accuracy. To expedite locating the optimal frontier point, We also eliminate spurious points by the obstacle filter and the novel boundary filter. In addition, we parallelize the global planning phase using the branch-and-bound A*, where the search space of each thread is confined by its best knowledge discovered during the parallel search. As a result, our parallel path-planning algorithm operating on 20 threads is about 30 times faster than the vanilla exploration system that operates on a single thread. Our method is validated through extensive experiments, including autonomous robot exploration in both synthetic and real-world scenarios. In the real-world experiment, we show that an autonomous navigation system using a human-sized mobile manipulator robot equipped with a low-end embedded processor that fully integrates our FFP and parallel path-planning algorithms.

Probabilistic volumetric mapping (PVM) represents a 3D environmental map for an autonomous robotic navigational task. A popular implementation such as Octomap is widely used in the robotics community for such a purpose. The Octomap relies on an octree to represent a PVM and its main bottleneck lies in massive ray-shooting to determine the occupancy of the underlying volumetric voxel grids.In this paper, we propose GPU-based ray shooting to drastically improve the ray shooting performance in Octomap. Our main idea is based on the use of recent ray-tracing RTX GPU, mainly designed for real-time photo-realistic computer graphics and the accompanying graphics API, known as DXR. Our ray-shooting first maps leaf-level voxels in the given octree to a set of axis-aligned bounding boxes (AABBs) and employ massively parallel ray shooting on them using GPUs to find free and occupied voxels. These are fed back into the CPU to update the voxel occupancy and restructure the octree. In our experiments, we have observed more than three-orders-of-magnitude performance improvement in terms of ray shooting using ray-tracing RTX GPU over a state-of-the-art Octomap CPU implementation, where the benchmarking environments consist of more than 77K points and 25K~34K voxel grids.

We propose a novel RGB-D camera tracking system that robustly reconstructs hand-held RGB-D camera sequences. The robustness of our system is achieved by two independent features of our method: adaptive visual odometry (VO) and integer programming-based key-frame selection. Our VO method adaptively interpolates the camera motion results of the direct VO (DVO) and the iterative closed point (ICP) to yield more optimal results than existing methods such as Elastic-Fusion. Moreover, our key-frame selection method locates globally optimum key-frames using a comprehensive objective function in a deterministic manner rather than heuristic or experience-based rules that prior methods mostly rely on. As a result, our method can complete reconstruction even if the camera fails to be tracked due to discontinuous camera motions, such as kidnap events, when conventional systems need to backtrack the scene. We validated our tracking system on 25 TUM benchmark sequences against state-of-the-art works, such as ORBSLAM2, Elastic-Fusion, and DVO SLAM, and experimentally showed that our method has smaller and more robust camera trajectory errors than these systems.

While visual tracking problem has been actively studied in computer vision discipline, recoginition and tracking objects beneath the water surface still remains a challenging problem since this problem open deals with several difficulties: 1) poor light condition 2) limited visibility 3) high turbidity condition 4) lack of benchmark image data, etc. Nevertheless, the importance of vision based capabilities in underwater environment cannot be overstated because, in these days, many underwater robots are guided by vision systems. In this research work, we propose an efficient and accurate method of tracking texture-free objects in underwater environment. The challenge is to segment out and to track interesting objects in the presence of camera motion and scale changes of the objects. We approached this problem with a two phased algorithm: detection phase and tracking phase. In the detection phase, we extract shape context descriptors that used for classifying objects into predetermined interesting targets. In the tracking phase, we resorted to meanshift tracking algorithm based on Bhattacharyya coefficient measurement. The proposed framework is validated with real data sets obtained from a water tank, and we observed promising performance of the algorithm.

We propose a robust and accurate method for multi-target geo-localization from airborne video. The difference between our approach and other approaches in the literature is fourfold: 1) it does not require gimbal control of the camera or any particular path planning control for the UAV; 2) it can instantaneously geo-locate multiple targets even if they were not previously observed by the camera; 3) it does not require a geo-referenced terrain database nor an altimeter for estimating the UAV's and the target's altitudes; and 4) it requires only one camera, but it employs a multi-stereo technique using the image sequence for increased accuracy in target geo-location. The only requirements for our approach are: that the intrinsic parameters of the camera be known; that the on board camera be equipped with global positioning system (GPS) and iner-tial measurement unit (IMU); and that enough feature points can be extracted from the surroundings of the target. Since the first two constraints are easily satisfied, the only real requirement is regarding the feature points. However, as we explain later, this last constraint can also be alleviated if the ground is approximately planar. The result is a method that can reach a few meters of accuracy for an UAV flying at a few hundred meters above the ground. Such performance is demonstrated by computer simulation, in-scale data using a model city, and real airborne video with ground truth.

We propose a robust and accurate method for multi-target geo-localization from airborne video. The difference between our approach and other approaches in the literature is fourfold: 1) it does not require gimbal control of the camera or any particular path planning control for the UAV; 2) it can instantaneously geolocate multiple targets even if they were not previously observed by the camera; 3) it does not require a geo-referenced terrain database nor an altimeter for estimating the UAV's and the target's altitudes; and 4) it requires only one camera, but it employs a multi-stereo technique using the image sequence for increased accuracy in target geo-location. The only requirements for our approach are: that the intrinsic parameters of the camera be known; that the on board camera be equipped with global positioning system (GPS) and inertial measurement unit (IMU); and that enough feature points can be extracted from the surroundings of the target. Since the first two constraints are easily satisfied, the only real requirement is regarding the feature points. However, as we explain later, this last constraint can also be alleviated if the ground is approximately planar. The result is a method that can reach a few meters of accuracy for an UAV flying at a few hundred meters above the ground. Such performance is demonstrated by computer simulation, in-scale data using a model city, and real airborne video with ground truth.