Advanced GIS Services Implementation

Tine Lesjak (2009) Advanced GIS Services Implementation. EngD thesis.

Preview

PDF Download (2808Kb)

Abstract

In the recent years we have experienced a renaissance in the field of geographic information. Navigation devices have penetrated into the everyday life. There is also an abundance of free web maps bundled with first-class services. Therefore, we expect them and even demand them. We came to a similar conclusion in our company, so I implemented three advanced services for the geographic information system that are very popular at the moment. The geocoding service finds addresses, streets or buildings that match a given search string. User chooses a locator and sets its properties, including a name of the place they are looking for. I also considered the full text searching, but which I didn't use for several reasons. The reverse geocoding service finds the nearest addresses, streets or buildings located in the nearby vicinity of a specified location. User chooses a locator, sets location coordinates and the working radius to be searched in. A method for computing the shortest distances is very important here. The best such method has proven to be a computation of distances on an Earth-shaped spherical model. The thesis contains other extensively tested methods, too. The routing service calculates the least expensive route from one location to another. User specifies a start and a goal location and two path evaluation functions. The A* algorithm is used, which speeds up the computation by using heuristic assumptions. One function estimates the path already handled; the second heuristically estimates the remaining path to the goal. All three services are built in the form of server services. They all use the same, newly developed, data model, in which the data is not duplicated. The model stores data universally for any location in the world and is flexible enough for any future expansions. Streets', buildings' and addresses' data is stored in a relational database and can use multiple geographical names. Object-relational mapping is used for communicating the data between the database and the server. The whole system is based on the Java technology. The result of this thesis is a fully-operational system, although it goes without saying, that the potential for improvements is enormous.

Actions (login required)