| This paper reviews the current employment and several development way of Web Geography Information System (WebGIS), The system structure ,methodology and construct modules of WebGIS is also presented . The advantages and disadvantages of the current widely used technologies of WebGIS is outlined. The technology symbols of some widely used WebGIS's software is compared in this paper, take ArcIMS——used in the system related of this paper as an example, it's structure and working methodology is described in detail. The framework of WebGIS-based Digital-Greenriver Spatial&Rainfall Information System is proposed. ASP programming language is used to obtain data in the database and guarantee the system's security. It's theorem in database manipulate and security mechanism is introduced in this paper. This paper introduces some spatial data interpolation theories. Take Greenriver valley as an example, considering the geography symbol of the valley, the system analyzing the rainfall information using the spatial analyze function of GIS .In order to establish valley rainfall analysis module, the valley is divided into regular cells, Kriging and Inverse Distance Weight(IDW) method is used to interpolate each node's rainfall. In the form of GIS thematic map , the result is showed as valley rainfall distribute map. Furthermore, an equal-value point search method is introduced in this paper to portray valley's rainfall equal-value lines based on the valley cells containing rainfall information. The results are promulgated on the Internet by valley WebGIS system. We compared the rainfall distribute map and equal-value rainfall lines achieved by Kriging method and IDW method . The result show us that Kriging method can express the rainfall nature disciplinarian better because of taking each node's diversity into account. |
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