3D magic

Time Team's surveyor, Henry Chapman, has the fascinating job of recording three-dimensional models of the landscape. These can be used to help viewers understand the landscape at large, and also serve as valuable tools in measuring and marking the exact locations of trenches for the archaeological record.

Henry uses a global positioning system (GPS) to calibrate his measurements. To make a good 3D model lots of points need to be measured three-dimensionally. One method of doing this is to set the equipment to 'kinematic track mode'. This means that the GPS receiver takes a reading automatically every few seconds and stores the data. A surveyor can then walk over the site and collect hundreds of measurements about the shape of the landscape as he goes. This data is then downloaded onto a computer, which creates a fully rendered digital terrain model of the landscape.