Ni H.,Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology |
Ni H.,Jiangsu Province Surveying and Mapping Engineering Institute |
Ni H.,Nanjing University |
Wu Z.,Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology |
And 8 more authors.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2016
In this paper we propose a raster line vectorization method based on Delaunay triangulation network. This method realizes the skeleton line extraction of line elements by spatiak subdivision of the raster line element using Delaunay triangulation network. This paper discusses raster map preprocessing, line element recognition, and the generation of edge point sets for line elements. A Delaunay triangular network is generated from edge point sets, and skeleton line extraction of line elements is based on tracing the midpoint of a Delaunay triangle public edge as the main technical line. We introduce implementation details of this vectorization process, and present the results of several experiments to validate the accuracy and timeliness of the method presented in this paper. © 2016, Wuhan University. All right reserved.
Tang X.,Satellite Surveying and Mapping Application Center |
Tang X.,Key Laboratory of Satellite Mapping Technology and Application |
Hu F.,Satellite Surveying and Mapping Application Center |
Hu F.,Key Laboratory of Satellite Mapping Technology and Application |
And 5 more authors.
Remote Sensing | Year: 2014
High-quality inner FoV (Field of View) stitching is currently a prerequisite step for photogrammetric processing and application of image data acquired by spaceborne TDI CCD cameras. After reviewing the technical development in the issue, we present an inner FoV stitching method based on sensor geometry and projection plane in object space, in which the geometric sensor model of spaceborne TDI CCD images is used to establish image point correspondence between the stitched image and the TDI CCD images, using an object-space projection plane as the intermediary. In this study, first, the rigorous geometric sensor model of the TDI CCD images is constructed. Second, principle and implementation of the stitching method are described. Third, panchromatic high-resolution (HR) images of ZY-1 02C satellite and triple linear-array images of ZY-3 satellite are utilized to validate the correctness and feasibility of the method. Fourth, the stitching precision and geometric quality of the generated stitched images are evaluated. All the stitched images reached the sub-pixel level in precision. In addition, the geometric models of the stitched images can be constructed with zero loss in geometric precision. Experimental results demonstrate the advantages of the method for having small image distortion when on-orbit geometric calibration of satellite sensors is available. Overall, the new method provide a novel solution for inner FoV stitching of spaceborne TDI CCD images, in which all the sub-images are projected to the object space based on the sensor geometry, performing indirect image geometric rectification along and across the target trajectory. At present, this method has been successfully applied in the daily processing system for ZY-1 02C and ZY-3 satellites. © 2014 by the authors.
Wang Y.,Jiangsu Province Surveying and Mapping Engineering Institute |
Li X.,Jiangsu Province Surveying and Mapping Engineering Institute |
Liu W.,Jiangsu Province Surveying and Mapping Engineering Institute
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | Year: 2013
To solve the problem that positioning the cable vibration in cable-stayed bridge's towing-cable suspended-wagon in a direct way is difficult, an indirect positioning technology is studied. First, according to the relative relation of the real elevation and the cantilever's elevation, a coordinate correction model for the cable vibration is established. The cable duct and stretching institution are changed from the design state into the real state. Then, a cable duct's independent coordinate system is established. Some cable duct's feature points are set at any position. The cable duct's real posture is obtained by measuring the feature points' coordinate and calculating the relation between these points and the cable duct. The cable duct is positioned indirectly in the independent coordinate system. The formula of relative relation between the cable duct and the stretching institution is also established. The positioning elements of the stretching institution are decomposed by the analytic geometry method. The stretching institution is positioned indirectly. The results show that this indirect positioning method can eliminate the effect of stretching institution caused by swing with cantilever and cantilever's presenting-height. The positioning procedure of the stretching institution can be simplified, and the positioning process is simple and intuitive.
Wang K.,Nanjing University |
Chen B.,Jiangsu Province Surveying and Mapping Engineering Institute |
Wu G.,Nanjing University
2010 18th International Conference on Geoinformatics, Geoinformatics 2010 | Year: 2010
Edge detection is important to image processing, and there are many approaches to detect the edge features from image. However, the high-resolution remotely sensed imagery including complex features is difficult to extract the edge features. This paper introduces a new method to detect edge from the high-resolution remotely sensed imagery. By using FFT, the high-resolution remotely sensed imagery is transformed into the magnitude spectrum image (frequency image). Then, the frequency image is analyzed by the Radius sampling and angle sample. Finally, Gabor filter is used to extract the edge features by setting the proper parameter. The experimental result shows that the proposed method gives a better solution for extract edge feature from the high-resolution remotely sensed imagery.
Li X.,Jiangsu Province Surveying and Mapping Engineering Institute |
Liu W.,Jiangsu Province Surveying and Mapping Engineering Institute |
Huang B.,Jiangsu Province Surveying and Mapping Engineering Institute |
Yu Y.,Jiangsu Province Surveying and Mapping Engineering Institute
Journal of Geomatics | Year: 2013
An improved cable duct' s precision positioning method in cable-stayed bridge was put forward in this paper. A cable duct's independent coordinate system was built and the 3D coordinate components of describe cable duct was changed to river direction, perpendicular to duct's direction and cable's direction.A reference point was setting out and was used to direct the cable duct's installing.Practice shows that the cable duct could reach to a very high accuracy when using this method.