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Open Source 3D

The modelling script uses Blender's Python API to generate a 3D scene from that tridimensional surface. Blender is an open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback. It is well known among the FOSS community.

The scene is stored as a “.blend” file by default. Another option is the generation of a X3D scene. Albeit X3D has some limitations, if compared to Blender, it is an open format, widely recommended by the World Wide Web Consortium (W3C) and fully integrated with the most used web-browsers (although it requires an additional plug-in in order to be correctly shown). X3D is a XML-based format and has evolved from VRML.


Fig. 2 Random curves from which the tri-dimentional mesh was extracted

After the generation of the X3D file, the model is exported to the browser, and can be freely viewed by the user. Figure 1 explains graphically the procedures described above.

Procedures and Examples
In order to test how Open 3D GIS works, a random set of level curves (generated automatically by a script developed at OpenGEO) was loaded into MapServer (Figure 2). This experiment is widely accessible through the web address http://www.opengeo.com.br/ms/o3dg/ At first, the whole area is loaded into the browser window. After that, the user can select a subset of that area, that will be seen in a larger zoom. When ready, it is possible to generate the 3D rendering of the selected area, through a button located at the left of this window.


Fig. 3 X3D renderings for the study area

Conclusions
This article shows the first steps towards fully integrating MapServer in order to provide a full 3D web environment. This first version of Open 3D GIS serves for visualization purposes only, and was developed with the intent to experiment the trade-offs of dealing with 3D data through the web.

Even though the results shown here are somehow very simple, it is expected in the near future that new versions should include the capability of representing 3D objects, such as buildings, roads and trees, and a basic query model, with which the user will be able do ask the database about such 3D objects. In next versions, Blender will be removed from Open 3D GIS and the solution will work on a pure X3D engine. Also, through the project's official page, located at http://www.open3dgis.org, it is possible to download the current version of Open 3D GIS. It is distributed through the GNU GPL license and has also a SourceForge project page, located at http://sourceforge.net/projects/open3dgis..
NOTE: The entire article with full references can be found at
www.gisdevelopment.net/magazine/asia/years/2007/Apr