Analysis of Spatial Autocorrelation for Point Objects based on Line Buffer

Jiangping Chen and Jingchao Jiang
School of remote sensing Information Engineering Wuhan University Wuhan Hubei, China
chenjp_lisa@ 163 .com; 77068177@qq.com

Abstract: In the light of Tobler's first law: everything is related to everything else, but near things are more related than distant things. This kind of relations called spatial autocorrelation. Spatial autocorrelation occurs when values of a variable sampled at nearby locations are more similar than those sampled at locations more distant from each other. Moran's I maybe one of the oldest and best indices for spatial autocorrelation. The ways of weight matrix definition will affect the value of Moran's I greatly. Since some weight matrix cannot differentiate the strength of spatial linkages between adjacent locations, some more complex spatial weight matrices are proposed for more precise spatial linkages. There are many ways to define a spatial weight matrix. For example: Rook's weight matrix, Queen's matrix, Binary connectivity matrix, K nearest matrix and distance threshold matrix etc. For point objects in the real world, the distance between the point objects is not the only feature affect their autocorrelation which were more affected by their accessibility. For example the autocorrelation of two cities, it's more affected by roads and the accessibility of the two cities than the distance between. It's naturally to consider the spatial autocorrelation for point objects based on the line between them. One new form of spatial weight matrix for point objects based on line buffer is provided in this paper. There are 3 steps in the paper. First, the line buffer range of the point objects according to the theme knowledge of the research fields is set. Second, the relationship of two point objects is defined by line buffer. If the point objects are both within the line buffer then they are spatial related and will be measured by a formula which offered in the paper otherwise their spatial autocorrelation is considered zero. Third, the method is applied in Moran's I. The experiment on spatial autocorrelation of the prices of buildings were applied in the new method, it shows that the method is effective.

Keywords: Spatial autocorrelation;Spatial weight matrix; Moran's I; Point objects; Line buffer

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