GPS tracking using a Trimble device
Earlier this summer we had the chance to cycle around London with an expensive, high-accuracy GPS tracker from Trimble.
More recently, we had the chance to do something useful with the data we recorded, the result of which was two separate maps based on the same data, and on the same general principle.
For each map we used three sources of data. The first was the raw data from the GPS unit (after post processing to get the sub metre accuracy), recording just over 850 individual co-ordinates. (Note the airplane showing in Bloomsbury Square was in fact at 8,000 feet rather than landing at the time!)
The second was a cleaned up version of the raw data, eliminating most points along straight lines – this gave us a still rather accurate route for only 140 points.
The final source of data was tracking the GPS location using a Google Nexus Android Smartphone, which was decidedly less accurate, and rather more wobbly:
The map we created from these routes has the option to switch between these sources, so you can see how accurate the raw data is, how clean the clean data is, and how wobbly the Smartphone data is: http://www.earthware.co.uk/client-stories/StreetView/LondonGPS.aspx
This map also plotted the elevation of the route, using the Google Maps API’s built in Elevation Service. Using the Elevation Service results in a column chart underneath the map, showing a remarkable dip on the east side of Russell Square. Additionally, clicking any column on the column chart will move the map and the Street View panorama to that location on the map, making it easy to see where the highest and lowest points on the route are.
We created a second map without the elevation data, and you can drag the bicycle icon around the route to move the Street View panorama with it. Simply click and drag the icon to any place on the map, and the Street View pane will update, allowing you to see exactly what you would see if you were riding your bike in London. http://www.earthware.co.uk/client-stories/StreetView/LondonGPSNoElev.aspx
Having the opportunity to work on this proof of concept was fantastic. It was amazing to see how much of a difference a professional GPS unit made in comparison to a built in tracker on a phone. Get in touch if you'd like to know more about what we did.