KEYWORDS: Clouds, Data modeling, 3D modeling, Reconstruction algorithms, Raster graphics, 3D scanning, Local area networks, Laser scanners, Laser applications, Image segmentation
An iterative slicing reconstruction method for point cloud surface holes is proposed to address the problem that the traditional hole repair method fails in repairing surface holes with uneven density. Firstly, the least squares micro-slices are used to detect and extract the point cloud hole boundaries, and then the least enclosing box is constructed and initially rasterized to achieve a uniform segmentation effect. Then the density of segmentation results is analyzed and judged, and if the density is too large, iterative slicing calculation is performed to obtain uniformly dense segmentation blocks. Finally, the moving least squares method is used to fit each slice data to reconstruct the missing part of the point cloud surface. Our results show that this method can achieve the effect of filling the point cloud holes and averaging the point cloud density as well as improving the accuracy of hole repair for holes containing curved surfaces or point cloud data with uneven density.
KEYWORDS: Clouds, Image segmentation, Reconstruction algorithms, Data modeling, 3D scanning, 3D modeling, Nonlinear filtering, Feature extraction, Local area networks, Image processing
Accurate segmentation of building facade point clouds is the key to 3D reconstruction of buildings. The region growing algorithm is widely used because of its simplicity and ease, but the traditional region growing algorithm leads to over-segmentation and under-segmentation problems due to the low robustness of seed points and the large differences in local features of building facade point clouds. To address the above problems, this paper proposes a building facade division based on FPFH feature classification and regional growth. Firstly, Kd-Tree is constructed to spatially index the facade point clouds and construct geometric topological relationships for the cluttered point clouds. Then, FPFH feature values are calculated and sorted for classification, while the points with relatively low feature values are selected as the initial seed points to ensure the stability of the seed points. Finally, the initial seed points are used as the reference for regional growth and face slice segmentation of the building facade point cloud. The experimental results show that the correct rate of the method in this paper is improved by 14.60%, the over-segmentation rate is reduced by 86.20%andtheunder-segmentation rate is reduced by 43.13% compared with the region growing algorithm, which not only improves the over-segmentation and under-segmentation problems, but also increases the segmentation accuracy as well as efficiency.
With the rapid development of modem technology, the digital information management and the virtual reality simulation technology has become a research hotspot. Virtual campus 3D model can not only express the real world objects of natural, real and vivid, and can expand the campus of the reality of time and space dimension, the combination of school environment and information. This paper mainly uses 3ds Max technology to create three-dimensional model of building and on campus buildings, special land etc. And then, the dynamic interactive function is realized by programming the object model in 3ds Max by VRML .This research focus on virtual campus scene modeling technology and VRML Scene Design, and the scene design process in a variety of real-time processing technology optimization strategy. This paper guarantees texture map image quality and improve the running speed of image texture mapping. According to the features and architecture of Guilin University of Technology, 3ds Max, AutoCAD and VRML were used to model the different objects of the virtual campus. Finally, the result of virtual campus scene is summarized.
KEYWORDS: Doppler effect, Satellites, Satellite navigation systems, Smoothing, Global Positioning System, Earth observing sensors, Receivers, Data analysis, Statistical analysis, Signal to noise ratio
GNSS (Global Navigation Satellite System) technology not only in the general field of surveying and mapping, geology,
mining, water and electricity, and in particular in the field of public security, fire protection, tourism, search and rescue,
adventure have been more widely used. These special areas require real-time and high positioning accuracy. Currently,
GNSS precision positioning technology has become a hot research direction. This paper introduced an algorithm of
smoothing pseudo range by Doppler based GPS/BD, to improve GNSS positioning precision. This algorithm decoded
the pseudo range data and ephemeris data, and then designed algorithm of smoothing pseudo range by Doppler
according principle of Doppler smoothing pseudo range. This algorithm was realized by C++ and proved its efficiency.
At last, this algorithm has proved its correctness through calculating and analyzing practical Doppler and pseudo range
data, and then a conclusion has been obtained: the Doppler value precision is sub-meter, far better than the pseudo-range
accuracy, so that if the two data are combined to calculate position that can help to improve the positioning accuracy.
In the investigation of China present road state and optimum designing of road, the linear data collection and computing of relevant parameters are very important. Though the methods of collecting data are feasible, but the methods of computing design parameters of road are lacking. This paper discusses that the theory of condition adjustment applies in road data collecting and optimum designing of road. The method goes as follows: after the road line types, mileages, curvatures of two endpoints of the road have been known, considering the constraint conditions on the distances between road and buildings on both sides of the road, we adjust all parameters of line type using the theory of Condition adjustment so that they satisfy a series of objective requirements while considering the condition that the curvatures of road should be continuous. This method has proved its availability by Visual C++ programming finally.
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