To correctly capture spatial targets from cluttered and motive celestial background,a new Multi-Target Capture algorithm was proposed,which is a comparative difference algorithm based on the combination of centroid ex...To correctly capture spatial targets from cluttered and motive celestial background,a new Multi-Target Capture algorithm was proposed,which is a comparative difference algorithm based on the combination of centroid extraction and despun registration of efficient points.Moreover,this algorithm was applied in an image processing system based on the DSP featuring high speed and high performance.The procedures of image processing are as follows:first,label efficient points in the frame and extract their centroids;second,make appropriate despun registration,according to the reference rotation angles provided by Space Robot position system;third,translate and register centroid coordinates of efficient points in reference frames and get the registration points according to the principle that there are the most same centroid coordinates of efficient points when completely registered;finally,eliminate the same background points by using comparative difference method.The result shows that this image processing system can meet the needs of the whole system.展开更多
The characteristics of urban space expansion reflect the changes of urban space layout and space structure, as well as the urban developing direction and urban orientation in the future. Based on the remote sensing im...The characteristics of urban space expansion reflect the changes of urban space layout and space structure, as well as the urban developing direction and urban orientation in the future. Based on the remote sensing image data of 1990, 2000, 2010 and 2020, this paper analyzes the urban space expansion characteristics of Luoyang, by using the urban land compaction index, expansion intensity index and centroid distribution in 4 time sections and 3 periods. The results show that: 1) the urban land area of Luoyang has expanded rapidly, the urban planning policy has successfully guided the urban expansion. 2) In the first period, the urban expansion belongs to the rapid expansion type, mainly filling the built-up area and natural expansion to outward;the second period is of high-speed expansion type, the urban expansion mainly enlarges the urban framework, then fills the expanded district, and the influence of urban natural growth factor is very small;the third period belongs to the high-speed expansion type, and the expansion rate is significantly lower than that in the second period, the urban expansion is mainly to fill in the urban framework enlarged in the previous period<span><span><span style="font-family:;" "=""> and</span></span></span><span><span><span style="font-family:;" "=""> continue to enlarge the urban framework, and the influence of urban natural growth factor is very little. 3)</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "="">The urban land centroid gradually migrates to the southeast with the azimuth of 151.47</span></span></span>°<span "="">, the annual migration distance is of 138.29</span><span "=""> </span><span "="">m. The migration rate in the second period is the fastest, which is about 7.43 times that of the first period, and 2.70 times that of the third period. In the first period, the urban land is mainly expanded to southward, with the main azimuth of 201.13<span style="white-space:normal;">°</span>. Compared with the urban land centroid in 2000, the urban land in the second period mainly expands to east-southeast and southward along the azimuths of 141.92<span style="white-space:normal;">°</span> and 154.17<span style="white-space:normal;">°</span> respectively. Compared with the urban centroid in 2010, the urban land in the third period mainly expands in the orientations of southeast and eastward along the azimuth of 96.24<span style="white-space:normal;">°</span> and 133.45<span style="white-space:normal;">°</span>.</span>展开更多
文摘To correctly capture spatial targets from cluttered and motive celestial background,a new Multi-Target Capture algorithm was proposed,which is a comparative difference algorithm based on the combination of centroid extraction and despun registration of efficient points.Moreover,this algorithm was applied in an image processing system based on the DSP featuring high speed and high performance.The procedures of image processing are as follows:first,label efficient points in the frame and extract their centroids;second,make appropriate despun registration,according to the reference rotation angles provided by Space Robot position system;third,translate and register centroid coordinates of efficient points in reference frames and get the registration points according to the principle that there are the most same centroid coordinates of efficient points when completely registered;finally,eliminate the same background points by using comparative difference method.The result shows that this image processing system can meet the needs of the whole system.
文摘The characteristics of urban space expansion reflect the changes of urban space layout and space structure, as well as the urban developing direction and urban orientation in the future. Based on the remote sensing image data of 1990, 2000, 2010 and 2020, this paper analyzes the urban space expansion characteristics of Luoyang, by using the urban land compaction index, expansion intensity index and centroid distribution in 4 time sections and 3 periods. The results show that: 1) the urban land area of Luoyang has expanded rapidly, the urban planning policy has successfully guided the urban expansion. 2) In the first period, the urban expansion belongs to the rapid expansion type, mainly filling the built-up area and natural expansion to outward;the second period is of high-speed expansion type, the urban expansion mainly enlarges the urban framework, then fills the expanded district, and the influence of urban natural growth factor is very small;the third period belongs to the high-speed expansion type, and the expansion rate is significantly lower than that in the second period, the urban expansion is mainly to fill in the urban framework enlarged in the previous period<span><span><span style="font-family:;" "=""> and</span></span></span><span><span><span style="font-family:;" "=""> continue to enlarge the urban framework, and the influence of urban natural growth factor is very little. 3)</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "="">The urban land centroid gradually migrates to the southeast with the azimuth of 151.47</span></span></span>°<span "="">, the annual migration distance is of 138.29</span><span "=""> </span><span "="">m. The migration rate in the second period is the fastest, which is about 7.43 times that of the first period, and 2.70 times that of the third period. In the first period, the urban land is mainly expanded to southward, with the main azimuth of 201.13<span style="white-space:normal;">°</span>. Compared with the urban land centroid in 2000, the urban land in the second period mainly expands to east-southeast and southward along the azimuths of 141.92<span style="white-space:normal;">°</span> and 154.17<span style="white-space:normal;">°</span> respectively. Compared with the urban centroid in 2010, the urban land in the third period mainly expands in the orientations of southeast and eastward along the azimuth of 96.24<span style="white-space:normal;">°</span> and 133.45<span style="white-space:normal;">°</span>.</span>