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Implementing Web GIS Applications using Open Source Software V. Raghavan Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, Japan Email : raghavan@media.osaka-cu.ac.jp P. Santitamont Survey Engineering Department, Chulalongkorn University, Bangkok, Thailand S. Masumoto Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, Japan K. Honda ACRoRS, Asian Institute of Technology, Pathumthani, Thailand
Introduction
Internet based geographical data services involve management spatial and non-spatial (attribute) data. Geographic Information System (GIS) has come to be an indispensable tool for analyzing and managing spatial data. Data pertaining to spatial attributes can be efficiently managed using Relational Database Management System (RDBMS). The development of a Web-based system by integrating GIS and RDBMS would serve two crucial purposes. Firstly it would allow the user to operate the system without having to grapple with the underlying intricacies of GIS and RDBMS technology. Secondly, it would allow sharing of information and technical expertise among a wide range of users. In the present paper we describe the salient features of spatial database that was developed by integrating the Open Source Software (OSS) GRASS GIS and PostgreSQL Object-Relational database into a Web based client/server environment. The system described in this paper aims at providing a web-based platform for collaboration and data sharing between specialists, planning agencies, citizens, and private entities. In order to access the spatial database, the user need only have a Web browser and access to the Internet. The system can be used to readily build and manage spatial databases pertaining to landslides (RAGHAVAN et al. 2001) and is presently being adapted to suit other applications such as a Water Infrastructure Inventory System (RAGHAVAN, HERATH & DUTTA 2001). Since the system is developed using OSS, it can be easily implemented in a distributed spatial database environment at a low overall cost. In this presentation we discuss salient features of an online system that offers public access to landslide information related to Japan (Japan Society of Landslides, 1996). The basic framework of the system is shown in Figure 1. Further, we also present an overview of our ongoing efforts to improve the interoperability and compliance with the OpenGIS Consortium (OGIS) Web Mapping Testbed (Web Mapping Testbed).  Figure 1 Components and Information Flow within the Prototype System GIS Component GRASS (Geographical Resource Analysis Support System) was used to provide the basic GIS framework. GRASS GIS was originally developed at the United States Army, Construction Engineering Research Laboratory. Presently, the development and distribution is coordinated by the GRASS Development Team (http://www.geog.uni-hannover.de/grass/ index2.html) and is made available under the GNU General Public License (http://www.gnu.org). GRASS is a hybrid vector-raster GIS designed to provide digitizing, image processing, map production, and GIS system capabilities to its user. GRASS contains several routines for importing spatial data of a wide variety of commonly used formats. GRASS files can also be directly imported into many commercially available GIS packages or exported to suitable data formats. The spatial data included in prototype system consists of GRASS raster, vector and site data layers that provide the geographical reference. |