The Development of Web-based Coordinate Transformation Service of Thailand

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The Development of Web-based Coordinate Transformation Service of Thailand

Sanphet Chunithipisana, *Soravis Supavetchb and Chaiwat Promthongc

a Department of Survey Engineering, Geo-Image Technology Research Unit, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand; CLOAKING

b Department of Survey Engineering, Geo-Image Technology Research Unit, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand; CLOAKING

c Geodesy and Geophysics Division, Royal Thai Survey Department, Bangkok, Thailand;

KEY WORDS: Coordinate Transformation Service, Web Processing Service

ABSTRACT: Geodetic datum defines the size and shape of the earth and the origin and orientation of the coordinate systems used to map the earth.  Hundreds of different datum has been used to frame position descriptions.  Geodesy and Geophysics Division, The Royal Thai Survey Department (RTSD) is responsible for the establishment of Geodetic Control Network in Thailand using the Global Positioning System, had derived three transformation parameters ( ) for transforming coordinates between coordinates based on local Indian1975 datum  and WGS84 datum for supplying to other authorities of Thailand.  In geographic information system, open source and commercial GIS software also provide a tool to transform geographic data to the any local coordinates.  That providing tool of those GIS software use different parameters and equations in coordinate transformation.  The result of that transformation differs from using our derived parameters.  From that inaccurate result, geodetic engineering projects in Thailand were affected.  Thus, RTSD has a plan to develop Web-based Coordinate Transformation Service of Thailand (WCTSoT) for providing a suitable and accurate tool for regional use.  In this paper, we report the development and discussion of that WCTSoT.  The standard specifications such as OGC WPS and WCTS were selected to implement WCTSoT.  Finally, the comparison between using our service and commercial software are also reported in this paper.