A Touring Machine: Prototyping 3D Mobile Augmented Reality System for Exploring the Urban Environment

S. Feiner, B. MacIntyre, T. Höllerer (1997)

This article written by three students in computer science that developed a device for exploring urban areas through the utilization of augmented reality (AR) for providing the user with extra useful information about the surrounding areas. The device was used in the campus of the Columbia University in New York and it was meant to guide the user with information about the different buildings and departments that exist within that campus. The device consist of three main parts:

1. a head mounted display (HMD) that allowed the user to see the real world through two little monitors, each for each eye. A camera is mounted in front of the right eye-monitor to get the images from the real world. 
2. a backpack carrying a portable computer that runs all the application, a GPS receiver and antenas for receiving and sending the wireless Internet signal from a server in the campus. 
3. a tablet computer with wireless Internet and a stylus for selecting elements on the screen. 

As the user walks around the campus he can see the real world through the HMD that gets the images from the tiny video camera in the right eye. The system knows the exact location of the user thanks to the GPS receiver and in combination with accelerometers and a compas inside the HMD the system senses in which direction the person is looking. The computer then feeds the system with text labels that are superimposed over the images from the real world that the user is seeing. These labels are overlaid exactly (or almost exactly) upon each one of the buildings surrounding the user and they provide him with information that allows him to identify each of those buildings. The tablet computer that the user is carrying is wirelessly connected with the information displayed in the HMD so that he can click on the labels using the stylus in order to get extra information about the selected item. This information is taken from the internet and wirelessly fed into the tablet from one of the many servers in the campus. 

This device was a prototype model and although the results were quite satisfactory, there were several technical issues that must be adressed. The quality of tracking, although it was in many cases sufficiently good, it is clear that for many potential uses of this technology the tracking accuracy must be much higher. New and improved internal sensors such as accelerometers, gyroscopes and magnetic compas will be needed to improve the precision or even the use of other additional technologies yet to be developed such as optic guidance with lasers or other similar technology. The loss of tracking was another frequent problem. In order to get a precise geo-location, a sufficient number of GPS satellites must be visible. The problem is that the signal from these satellites is very weak and it can easily be blocked by surrounding buildings or even foliage. This problem becomes even greater when these AR devices might be required to be used indoors.

The students were, however, very pleased with the results and excited over the many possibilities that this technology could offer in a near future.