矢量景观指数在遥感信息提取中的应用--以乾安湖群为例

The Use of Vector Analysis Theory on Landscape Pattern in Remote Sensing Information Extraction:A Case Study on Qian-an Group Lakes

景观方向性是景观空间格局的重要特征,能够反映和影响景观的生态流。实现快速、准确地从遥感影像上自动提取景观的方向性信息,对于景观的驱动力分析和景观异质性分析等都具有十分重要的意义。本文基于面向对象的方法对乾安县TM影像进行多尺度分割提取湖群,并利用正方像元指数SqP提高分类精度,应用矢量景观指数于分割处理后的湖群对象,提取景观的方向性信息。实验结果表明:该方法对象分割精度高(制图精度:97.8%,用户精度:97.5%),方向性信息提取准确、快速,为湖群的成因分析提供了数量化和可视化依据。本文同时结合了两方面的研究方法,提供了两方面的研究思路:一方面是景观格局指数在影像分类中的应用,另一方面是矢量景观格局理论进一步的应用扩展。

Pattern directionality is a key characteristic of landscape pattern,it both reflects and affects ecological flow within the landscape,and it is very important to realize fast and accurate auto-extraction of the pattern directionality information,especially for landscape heterogeneity analysis and driving forces analysis.Qian-an county lies in the northwest of Jilin Province in China,where the climate is characterized as temperate semiarid continental monsoon,the evaporation greatly exceeds the precipitation.Wind,especially the strongly prevailing wind in winter from northwest to southeast plays an important role in shaping some local landscapes.For most time of the year,the weather is extremely dry and the soil is sandy and uncovered.There are many lakes,known as Qian-an Group Lakes in Qian-an county.The lakes are typically small,and the water in the lakes is salty,seasonal and shallow,commonly about 1—2m deep.The lakes are mostly in the shape of a raindrop,with gently sloping lake beds in each lake's northwest(the windward side),and a steeply sloping lake beds in the southeast(the down wind side) with dune or loess piling up on this side.Wind is considered to be one of the most important forces driving the pattern formation of the lakes,i.e.,the current shape of the lakes is the result of windy erosion upon the tectonic basins.In order to provide a quantitative and visual basis for the above mentioned conclusion conveniently and objectively,based on object-oriented method Qian-an Group Lakes are extracted by multi-resolution image segmentation from Qian-an TM image.To achieve the high classification accuracy,a perimeter-area shape complexity metric called the Square Pixel Metric(SqP) is used,then vector analysis theory on landscape pattern(VATLP) is applied to the homogeneous objects to extract vector information of group lakes.Where,vector analysis theory on landscape pattern(VATLP) is developed by Shuqing Zhang et al.(2006) based on planar characteristics defined in mechanics such as centroid,moment of inertia,product of inertia and principal axes,and its application helps us better understand the pattern formation of the lakes and the related ecological processes that occur on both ends of the major principal axis,e.g.,the transportation of energy and materials flow,and the ecological gradients.The experimental results show that our method achieves the high segmentation accuracy(producer's accuracy: 97.8%,user's accuracy: 97.5%),and extraction of directionality information is accurate and convenient.This can establish the groundwork for the further geographic analysis.This paper offered two-aspect idea: one is the use of landscape pattern metrics in image classification,the other is the further application of vector analysis theory on landscape pattern (VATLP).