While the real world is three-dimensional, or even fourdimensional if we add time, geographic information systems (GIS) are generally constrained to just two dimensions. Progress toward three-dimensional GIS has been made in data acquisition methods (both through terrestrial and remote sensing) and visualization techniques (driven by computer graphics); however, deficiencies remain in 3D data analysis due to the lack of a 3D topology embedded in GIS. Therefore, commercial GIS are generally not capable of meeting the requirements of a fully functional 3D GIS.

This entry begins by outlining the necessity to consider the third spatial dimension to get results that represent and analyze the real world precisely. The 3D capabilities of typical GIS are briefly described in terms of data acquisition, modeling, analysis, and visualization. Graphic ...