Ordnance Survey – Great Britain's national mapping agency
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2.6: The third dimension (3)
Realistic models
These 3-D models can be made to look very realistic by applying colour to the surfaces. It is even possible to drape raster images of maps or aerial photos over the surface with quite stunning effect. Furthermore, if the heights of physical objects like buildings, forests and electricity pylons are known, these can also be built into the 3-D model. Hence it is possible to create computer models of entire towns and villages which relate directly to the real world.
The ability of GIS to operate in three dimensions has many useful applications, for example:
- visualisation of the 3-D landscape;
- calculation of gradients for roads and railways;
- environmental impact analysis for engineering projects;
- screening of objects such as power stations and wind turbines through line of sight analysis;
- radio wave propagation analysis – important to mobile communication networks;
- flood risk analysis;
- town planning; and
- leisure products – many computer games use realistic landscapes based on GIS height data.
Below are a selection of thumbnail images showing different types of 3-D view captured from GIS, have a look at them to see just how effective these visualisations can be. Try downloading the animations for a glimpse of how GIS can build entire virtual worlds.
And now for something completely different. Topology is one of the most revered examples of jargon in the whole subject of GIS. The next section demystifies this term, which is actually rather important: Section 2.7 – Topology. It's all about relationships.
Flythroughs
