The development of programmatic algorithms for on-demand map editing for Internet users with GML and SVG

Abstract

The widespread availability of the World Wide Web has led to a rapid increase in the amount of data access, sharing and dissemination. This gives opportunities for delivering maps over the Internet. In the geometics industry, many vendors or companies have produced their own Web map products with their own versions, data models and proprietary data formats. These may not able to communicate with each other. Such problem has long been an issue and therefore Geography Markup Language (GML) was designed to help solve the above problems. GML is an XML grammar written in XML Schema for the modelling, transport, and storage of geographic information including both spatial and non-spatial properties of geographic features. It was developed by Open GIS Consortium in order to promote spatial data interoperability and open standard. As GML is not for data display, Scalable Vector Graphic (SVG) is an ideal vector graphic for displaying geographic data. GML sits at the backend to store and transport data, while SVG sits at the frontend to render and display geographic data. There are already some applications on the basis of GML and SVG. These, however, are limited to display and view the maps only. In fact, GML and SVG not only can visualize geographic data on the Web, but also give the possibility to edit geographic data online. This research, therefore, is to develop efficient programmatic algorithms of editing geographic data online. It explores whether using GML and SVG is a good method to intergrate Web-based mapping information in terms of data modelling, spatial data presentation mechanism and spatial data editing capability. Especially in the Internet environment, it finds whether using GML and SVG can give significant improvements of bandwidth, speed, access and reliability. To demonstrate the idea for the study, a prototype was developed. It aimed to investigate the capability of GML and SVG and to develop a corresponding data model and a system, in order to overcome or improve existing limitations on online graphic presentation and data editing functions. The focus was on examining capabilities, specific problems and approaches in using SVG as a user interface for editing geographic data online. The major contribution of this study is the newly developed online method of spatial data editing. Geographic data can be edited and displayed at real time by using open source software. The data editing functionality is no longer limited on desktop GIS packages, but has been developed to be used on the Internet from making online editing possible for all users anywhere even without the assistance of sophisticated GIS tools.