Geometry and The Perfect Quad

Jul 5 2010

The last three months saw one of those painful and critical steps that few speak or care about: converting the elevation data to a 3D polygonal mesh that can be used in animations and real-time simulations.  We wanted to do it once and right, and assure that the final mesh could be easily used in any type of application.   The above image is the mesh created from the converted data. It is a view from Washington in 1790 looking NW across Roosevelt Island past Georgetown to the Great Falls and beyond.  For clarity, the mesh of the Potomac River is colored blue.  

To build a solid foundation for 1790 over the last year, we used arcGIS, the granddaddy of GIS software.  It is the perfect vehicle for all of the different databases of information we needed to bring together.  However, to move the elevation data to any 3D animation or video-game application, it needs to be converted.  Because of the vast amount of territory – we ended up with almost 300 square miles – and with the high resolution we needed, this was not easy.  We also elected to convert to a polygonal mesh and wanted very clean geometry made of quads (squares). To keep the mesh light weight, we wanted the quads in the outlying area large, but the ones downtown should be small to allow for high detail.  The quads need to be scaled correctly to each other and to the overall scale.   It took three months to convert the data, merge the meshes together, and assure that the final was perfectly scaled to any 2D images that we would also export from arcGIS.

Finally. Perfect. High-Res. Light weight. 300 square miles. Done.  Moving on. Bring on Pierre L’Enfant!

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