readme_pgsql.md

Rasterize roof heights

Creation of building roof heights raster from semantic 3D city models.
Roof heights are calculated as absolute height value as well as normalized to the ground.

Algorithm description

• Creation of regular point grid for the area covered by roofs
  • Raster cell size is predefined with 0.5 m, can be changed in temporary table tmp_raster_parameters
• Conversion of cell centroids to points
• Extrusion of points to vertical lines and
• Intersection between vertical lines and roof geometries
• Intersection results in points with roof height at given positions
• Storage of intersection points as table with x,y,z-values

Workflow

• Setup 3D City Database as described in this tutorial
• Import CityGML data to 3D City Database
  • if necessary, use tiled export to generate smaller tiles
• Run rasterize roof heights script on database
• Export table to space delimited CSV

Requirements

• 3D building model stored in a 3D City Database instance
• PostgreSQL database extensions postgis and postgis_sfcgal