3D Mapping: Buildings in Boston

After completing the Esri Training Course "3D Visualization Techniques", we were asked to convert 2D features to 3D features using data gathered from LiDAR.

First, the Esri course taught us the vocabulary of 3D - multipatches, Z-values, terrain data sets, TINs, rendering, and extrusion, for example.  After examining the elements of 3D data, we learned how to define base heights, then set about practicing these skills using a map of Crater Lake National Park.  Base height was set for various data types, including an elevation raster, a 3D feature class, a line feature class, a point feature class, and a raster vegetation layer.  Next we learned how to enhance 3D views using Vertical Exaggeration and Illumination.  In the last section we learned how to generate 3D Objects from 2D Objects.  In the exercise, we extruded Buildings and Wells, then added an aerial photo draped over an elevation TIN.  Another step was Extruding Parcel Values so that these differences would be reflected in the height and color of the buildings.

This course provided the skills necessary to complete the final part of the lab, in which a map with a 2D shapefile of buildings in Boston was converted into the 3D map above.  After the two layers were added (the raster base layer and the shapefile buildings layer), the base height was calculated.  Since the raster layer had the elevation information, a new layer was created with random points for each building which had the elevation information added to them. The Mean Z Value was calculated in the SamplePoints layer, then joined to the buildings layer. Once the 2D data had "Z" values, it was possible to create a 3D map by extruding the building features.  For people without access to ArcGIS, these maps can be saved as a .kml file  and can be viewed instead using Google Earth, for example. 

Maps created in 3D are quite attractive when done well.  The example map of Napoleon's Moscow campaign is a fantastic example of how easy and fun it is to view and interpret one of these maps when it is done well.  Being able to fly around, zoom in, explore in a virtual world is exciting.  Still, at this point the ability of most people to access these maps is limited, and there seems to be the potential for bad data and poorly created maps, as there are in 2D.  That said, it seems clear to me that the abilities of a 3D map to convey information clearly, quickly, and accurately, are far above those of 2D maps.