Digital terrain model （DTM） has played an important role in 3D designing, visual analysis and 3D geological modeling in large-scale hydropower engineering. As the pivotal base of 3D visualization and ...modeling, DTM should be characterized by high precision, less storage and well interactivity during graphic operation. Considering the diversity of data source and taking advantage of two data structures, triangulated irregular network （TIN） and non-uniform rational B-splines （NURBS）, a novel methodology is presented for reconstructing engineering terrain ofhydropower project. With integration of multi-source data, enhanced Delaunay algorithm is introduced to rebuild the TIN- DTM, which is a terrain surface in TIN and a faithful depiction of complex topography but in low-memory efficiency. Based on the TIN model, applying section scanning sampling and linear interpolation, the transformation from discrete, irregular and diverse data to continuous and regular sampling cross-sectional curve sequence, is realized. The appropriate compression of the sampling data is also imposed to be performed for guaranteeing the following reconstruction work. Eventually, employing the NURBS technique and skinning method, the NURBS DTM, which represents a NURBS surface and satisfies the requirement after precision assess with weighted errors, is reconstructed with the inter- mediate data. Meanwhile, there is another achievement that two databases of terrain data, one from initial data and the other from sampling data, are established for repeatable reconstruction with different demands. With the successful application of the presented method, a stable foundation is laid for 3D engineering geological modeling, visual designing and analysis of the hydropower projects.
An Interac table Topographical Map (ITM) is a generalization of the modern GPS-based applications, such as the Google Maps. In the case of an ITM system, the pinpointing, tracking, and augmenting of ...relevant information are presented on approximated 3D geographical terrains instead of 2D maps. Similar to GPS-based maps, an ITM system can support pre-planned journeys or explorations by augmenting appropriate journey information such as path and time to destination, traveling speed and direction. In contrast to traveling through urban traffics, an ITM system is better served as the guide or reference for journeying through undeveloped terrains. Such journeys are often required for missions into these regions, often critical and sometimes dangerous such as fighting forest fires, or search and rescues. The planning of such operations often involves the collaboration of various disciplinary experts and frontline personnel who may be distributed geographically. Additionally, especially for frontline personnel who must execute the potentially dangerous missions, the ability to be immersed in the actual 3D environment can be essential. This paper examines existing ITM systems, derives a design guideline, and discusses a prototype implementation that supports the collaboration of remote users across reality boundaries, i.e., users configured with distinct reality configurations, e.g., PC users and VR users. Though only an initial step, the delivered system demonstrated interesting potentials and insights.
This paper builds an Augmented Reality Sandbox (AR Sandbox) system based on augmented reality technology, and performs a 3D reconstruction for the sandbox terrain using the depth sensor Microsoft ...Kinect in the AR Sandbox, as an entry point to pave the way for later development of related metaverse applications, such as the metaverse architecting and visual interactive modeling. The innovation of this paper is that for the AR Sandbox scene, a 3D reconstruction method based on depth sensor is proposed, which can automatically cut off the edge of the sandbox table in Kinect field of view, and accurately and completely reconstruct the sandbox terrain in Matlab.
We present a technique to generate realistic high quality texture with no seams suitable to reconstruct large-scale 3D terrains. We focused on adjusting color difference caused by camera variations ...and illumination transition for texture reconstruction pipelines. Seams between separated processing areas should also be considered important in large terrain models. The proposed technique corrects these problems by normalizing texture colors and interpolating texture adjustment colors.
This paper presents a novel integrated approach of creating a 3-D surface map of seabed terrain using an Autonomous Underwater Vehicle (AUV) equipped with various sensors such as multi-beam sonar ...sensors, DVL, and IMU. The underwater terrain map is useful for various applications like fishery, search and rescue operations, underwater surveillance, mine hunting, etc. The acoustic sensors mounted on the AUV overcome the unfavorable underwater conditions like nonuniform illumination and restricted visibility. In the proposed methodology, the AUV is autonomously navigated using a navigation controller on a flat 2-D surface at a certain depth, to cover an a priori unknown area using an adaptive path planning algorithm. The terrain data is captured by the down-facing multi-beam sonar sensors. The Long Baseline (LBL) localization system and PID controllers are used to drive the AUV to the set-points given by the navigation controller. The collected data is then used offline to construct a 3-D map of seabed using alpha shapes. The performance of this method is tested and validated using a high-fidelity underwater simulator UWSim based on Robot Operating System (ROS). In the simulation runs, the proposed methodology is shown to reconstruct accurate 3-D maps of the seabed.
In order to solve the problem of indoor 3D terrain reconstruction, a 3D terrain reconstruction system based on Four-axis eight-rotor aircraft with binocular camera is constructed. The binocular ...camera is a shooting tool similar to the human eye that can recognize the depth of field. It is planned to use a self-made four-axis eight-rotor UAV with a binocular camera as the hardware foundation of the system. The drone can achieve accurate indoor positioning by installing an optical flow module. The depth of field image is returned in real time indoors. The receiving end collects the depth of field image of the binocular backhaul, and uses an image stitching algorithm based on the phase correlation method to determine the similar area and adopts the feature point matching method to realize the automatic stitching of the image. The system can use Open CV to represent stitched images as images of depth of field rendered in different colors. The system is used to carry out 3D terrain reconstruction experiments. The results show that the 3D terrain reconstruction images obtained by the system meet the actual needs, which proves that the system has an ideal reconstruction effect on the indoor three-dimensional terrain.
The reconstruction of 3D objects from a point-cloud is based on sufficient separation of the points representing objects of interest from the points of other, unwanted objects. This operation called ...segmentation is discussed in this paper. We present an interactive unstructured point-cloud segmentation based on graph cut method where the cost function is derived from euclidean distance of point-cloud points. The graph topology and direct 3D point-cloud segmentation are the novel parts of our work. The segmentation is presented on real application, the terrain reconstruction of a complex miniature paper model, the Langweil model of Prague.
This paper presents an autonomous approach of 3-D reconstruction of underwater terrain using multi-level coverage trees. An autonomous underwater vehicle (AUV) equipped with multi-beam sonar sensors, ...Doppler velocity log (DVL) and inertial measurement unit (IMU) sensors is used to achieve this goal. The underwater 3-D search space is represented by a multi-level coverage tree which is generated online based on the obstacle information collected by the AUV. The nodes of the tree correspond to safe sub-areas for AUV navigation which are identified based on obstacle density in neighborhood of free cells. Standard tree traversal strategies like depth-first-search (DFS) and breath-first-search (BFS) are then used for visiting all the nodes of the tree thus securing complete coverage of the 3-D space. The terrain data collected by the AUV during tree coverage is used offline for the 3-D reconstruction of seabed using alpha shapes algorithm. The performance of this method is validated using a high-fidelity underwater simulator UWSim based on Robot Operating System (ROS). The simulations show that the proposed methodology achieves safe path planning and accurate reconstruction of the 3-D map of the underwater terrain.
Lunar terrain reconstruction using PDEs Ji Liu; Yang Cong; Xiaomao Li ...
2008 15th IEEE International Conference on Image Processing,
2008-Oct.
Conference Proceeding
Based on the geometry features of lunar terrain, this paper treats lunar terrain reconstruction as a surface reconstruction problem. We define an energy functional model consisting of local energy ...term and smooth energy term for lunar terrain reconstruction. The solution to minimize the functional (by partial differential equations) is defined as the optimal surface. In the smooth energy term, we design a vector field of depth discontinuousness likelihood (VFDDL) to control the direction and degree of smoothing. Experiments indicate that accurate VFDDL can lead to an exact reconstructed surface. Thus, VFDDL transfers 3D terrain reconstruction into a 2D image processing problem. An innovative method is proposed to estimate VFDDL, using image local and statistical features. Experiments verify our method and show a good performance in terrain reconstruction.
Remote-control technology is required in an unmanned vehicle such that it can replace humans for executing tasks in various extreme environments. In particular, a remote scene must be reconstructed ...using 3D meshes for enabling a user to remotely control an unmanned vehicle easily and intuitively. To this end, a large amount of multiple sensor data would be processed using various algorithms in real time. Considering the limited hardware specifications in extreme environments, it is difficult to implement 3D terrain reconstruction in high-quality and real time. This paper proposes the optimization of the architecture of a multiple-sensor-data pipeline. The improved performance resulting from the optimized architecture was analyzed through experimental comparison with a non-optimized system.
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