Three-Dimensional Landscape Analysis Of Zhangye City Based On Lidar Data

With the accelerating process of urbanization, land resources become scarce and the city’s development faces a severe test. In order to evaluate the land use of the urban accurately and objectively, LiDAR and aerial imagery is combined in the object-oriented classification of the area. The analyze is of great significance for the evaluation of land use in urban area.Classification of the center of Zhangye city is implemented based on object-oriented classification method using LiDAR and aerial imagery. Landscape index is used to quantitatively analysis the spatial pattern of the area based on the classification result. The main contents of the study and its results are as follows:(1) The study of optimal segmentation scale. This paper studies the relationship between homogeneity, heterogeneity of the objects and the segmentation scale. An index based on heterogeneity and homogeneity is put forward to determine the optimal segmentation scale of single-band and multi-band data. The method is used for the determination of the segmentation scale in the classification using LiDAR and the scale is verified. It is also used to determine the segmentation scale of object-oriented classification method combining LiDAR and aerial imagery and the scale is also verified.(2) The object-oriented classification of the area. For different coverings, multi-scale segmentation is implemented according to its optimal scale, and then the area is classified based on the corresponding feature space and the fuzzy classification rules. First, the object-oriented classification is implemented using LiDAR data, and high-rise buildings, low-rise buildings and trees are extracted. The overall classification accuracy is91%. As characteristics of roads and lawns in LiDAR data are similar, we can not distinguish them only through LiDAR data. To solve this problem, we combine aerial imagery and LiDAR data in the classification and get high-rise buildings, low-rise buildings, trees, road and lawns finally. The overall classification accuracy is93%.(3) The analysis of landscape pattern. Two-dimensional and three-dimensional landscape indexes are selected to quantitatively analysis and evaluate the structure of the region’s landscape on the foundation of the classification. The results show that the development of urbanization makes the degree of fragmentation of the region become higher. The height of the building in the study area is significantly different and there are planning and tidy high-rise buildings as well as low-rise buildings, showing a scattered distribution.