Visualization of computer-generated 3D cities using GIS data

The constant performance increase of algorithms and hardware over the last decades enabled new ways to collect data, which would have been unthinkable just a few years ago. This is especially true in the sector of geodesy. The release of gps-tracking smartphones enabled users from all over the world to easily collect and upload georeferenced data. Additionally governments also started to make their georeferenced data available to everyone. Through these phenomenons countless databases containing georeferenced information appeared on the Internet. By accessing these databases numerous new applications can be implemented. This thesis focuses on the creation of three-dimensional models that can be easily integrated in a virtual reality environment. The practical part of this thesis consists of four steps. The first step is the data acquisition.As mentioned before nowadays there are various eligible data sources for such a project, however in this work all the data is fetched from a public database of the Austrian government. This database has been chosen because it already contains all required buildings’ footprints and heights. In the second step the acquired data is analysed and pre-processed using Matlab. By using the filters implemented in Matlab artefacts resulting from the noise contained in the data can be removed. In the third step a suite capable of combining the data-sets is presented. Quantum GIS offers a complete open source suite capable of combining, displaying, processing and exporting georeferenced data. This tool contains solutions for all the problems proposed during this step of the project. The final step is the implementation of the web-application, which creates the three-dimensional models by importing the files generated during the previous step. This web-application has been implemented using WebGL so that most of the calculations are done on the client’s graphics card. The three-dimensional models have been compared with the models offered by the Austrian government for the sake of showing that the presented framework is capable of producing similar models at a lower performance cost in a virtual reality environment. Practically, the presented framework has been implemented and its results have been tested during the course of another project, in which the city models were used in order to create a skydiving experience over the city of Vienna in a virtual reality environment. Over the course of the mentioned project the models were found satisfactory by the users.