Digital Map Making with GPS

This time in Hubei 湖北, we taught the high school students how to use the GPS (Global Positioning System) to make a digital map. A GPS receiver uses signals from a system of 27 satellites flying over the earth to determine the location it is at, in terms of longitude and latitude. (The GPS receiver has to be able to receive the signal from more than one satellite to determine its own position. Why? And from how many satellites?) This receiver is actually displaying the coordinates of a famous secondary school in Hong Kong. (Do you know which one it is?)

Walking around the campus with the GPS receiver in hand, we determined the location, shape and size of each landmark on campus, and then drew the campus map with some simple tools. The GPS readings could be off by a few meters or more, hence manual adjustments had to be made. We also took some pictures of the campus locations and linked them to the landmarks, making a clickable map.

It was a lot of fun for both us as tutors, and the high school students. A tremendous amount of preparation went into acquiring the proper equipment, designing the overall plan and specific tasks, doing the many trials and dry runs, coordinating the ~200 students involved in the data collection, and then finally integrating everything to make the map. I have some amazing colleagues and students who worked very hard together to pull the whole thing off. We are justifiably proud of what we have achieved. Now that we know the method works, it can be applied to other related tasks.