Game Development Reference
Gaming from One Place to Another
Once a tool meant to help the United States guide intercontinental ballistic missiles, the
Global Positioning System (GPS) has evolved to be a part of our everyday lives. The
current generation will never have known a world where getting lost was something
that couldn't be fixed by trilaterating their position between satellites orbiting the planet.
Although GPS has become commonplace in the navigational world, the proliferation
of smartphones is just now opening the doors to GPS gaming. While this genre is just
emerging, we'd like to give you an introduction to the physics behind GPS and the
current applications in the gaming world.
Let's recall that positions near the earth's surface are generally given in the geographic
coordinate system , more often described as latitude, longitude, and altitude. Latitude is
a measure in degrees of how far north or south you are from the equator. Longitude is
the measure in degrees of how far east or west you are from the prime meridian. A
meridian is a line of constant latitude that runs from the North Pole to the South Pole.
The prime meridian is arbitrarily defined as the meridian that passes through the
Greenwich Observatory in the UK. Altitude is usually given as the measure of how far
above or below sea level you are at the point described by latitude and longitude.
Before getting to the physics behind GPS, we'd like to take a moment to discuss how
GPS is being implemented into games. Right now, this is an emerging market that is
just starting to gain traction. There are several broad categories into which games fall.
Another step beyond what the accelerometer did, GPS enables users to move computer
games not only off the couch but also out into the world.