Rapid Extraction And Historical Change Analysis Of Lujiazui City Height Information Based On Google Earth

As the embodiment of the vertical space of urbanization,urban height information has important reference value and research significance in urban geography research.In recent years,how to achieve high-speed and accurate extraction of three-dimensional urban information has become one of the hot topics in the research of three-dimensional urban information extraction.Taking Lujiazui in Shanghai as the research area,this paper designs a high-precision and fast method to extract the height information of high-rise buildings in the city by using the shadow characteristics of buildings in Google Earth satellite images,and makes a preliminary study of three-dimensional spatial visualization of Lujia zui by obtaining the height data.This research mainly focuses on the following two aspects:1.Through investigating the theory of shadow imaging,radiation enhancement processing and studying the shadow characteristics of ground objects,a high-speed extraction method is designed and implemented,which can quickly distinguish the difference between building shadow and projection in image.The resolution effect between shadow and projection in image building is improved,and a more precise base position of building shadow is obtained,and 40 buildings are located.The maximum absolute error is only 25 meters,the av erage minimum error is about 5.4 meters,the height error is mainly in the range of 0-10 meters,and the relative error is mainly in the range of 0-5%,which further improves the data quality in meeting the efficiency of high-speede xtraction.In the follow-up study,the height information of 219 high-rise ands uper-high-rise buildings in Lujiazui Street was extracted quickly according to this method.2.The information of 219 high-rise buildings in Lujiazui was collected by Octopus collector and visual interpretation of satellite images,and the historical changes of the number of high-rise buildings in Lujiazui were compared and counted with the height data.The three-dimensional spatial distribution and sky line changes of urban height in six periods of 1990,1995,2000,2005,2010 and 2017 in Lujiazui were rapidly inverted.In this way,the research on the vertical variation characteristics of Lujiazui has been realized.