Constructing and serving buildings 2.5D

In the Detailed building footprints from LiDAR recipe in Chapter 4, Working with Vector Data - Advanced Recipes, we explored the automatic generation of building footprints using LiDAR data. What we were attempting to do was create 2D data from 3D data. In this recipe, we attempt the opposite, in a sense. We start with 2D polygons of building footprints and feed them into a function that extrudes them as 3D polygons.