Trap Grounds [Introduction]
GPS Area Map [N51.76953° W1.27235°]
The purpose of this commission was to calculate the accessible
area of the Trap Grounds in Oxford.
A map was produced by walking around the six acre site with hand-held GPS receivers.
The GPS receivers that were used (Garmin GPS 72) calculated their positions every two seconds
using trilaterated satellites signals. A total of 42.6 km (26.5 miles) of digital tracks were recorded
over a period of five hours. The tracks were copied to a computer, processed and edited to remove
acquisition lines and inconsistencies that are inherent to the technology.
The site was then re-visited with a copy of the original GPS map and a tape measure to establish exactly
how accurate the initial map was. It was discovered that accuracy was generally to within 4 metres,
with few stray lines venturing off by about 10 metres. These lines mostly occurred where sharp corners
were turned and under the densest tree cover.