Spatial Knowledge Acquisition in the Context of GPS-Based Pedestrian Navigation - Maps for the Future Children Education and Internet - page 129

11.2 Study Design
11.2.1 Study Route and Participants
A route in the city centre of Salzburg (Austria) was selected for the empirical test. It
was divided into three sub-routes, each with nine decision points (e.g., intersections
where multiple outgoing choices exist). The surroundings of these sub-routes are
characterized by residential and business areas.
Twenty-four participants took part in the study (12 female and 12 male). The
mean age was about 40 years (range 22-66). They were paid for their participation.
All of them are German-speaking people.
11.2.2 Navigation Prototypes
For studying wayfinding performance and spatial knowledge acquisition with
different interface technologies, we used three self-implemented mobile navigation
prototypes running on Apple's iPhone 4. These prototypes used map-based, AR-
based, and voice-based interfaces respectively. Recent findings on pedestrian
navigation from literature were integrated and considered when developing these
prototypes.
Figure 11.1 shows a screenshot of the map-based prototype. The route is
visualized as a red line filled with small white arrows pointing the forward direc-
tion. The past path is dyed in a lighter colour to be clearly separated from the future
path. The real-time position is determined by GPS, improved by a route matching
algorithm. A “track-up” egocentric map view is provided and its centre is adapted
automatically to the current location. When a user is close to a decision point, a
semi-transparent, blue-white directional arrow appears at the bottom-right of the
screen. The arrow shows the directions based on the 7-sector model proposed by
Klippel et al. ( 2004 ). Some other functions are also provided, such as zooming and
panning.
In the AR-based prototype, route information is overlaid on the real world
camera view. GPS module, magnetometer, and the tilt sensor on the mobile devices
are used to calculate the position of the overlay information. Depending on the
distance to the next decision point (DP), the overlay information changes from a red
circle marking the position of the DP, to a bigger red circle showing remaining
distance to the DP, and finally to a bigger red ring enclosing the waypoint to be
entered. By changing the style and enlarging the size of the overlay, we expect users
to get a feeling of crossing a portal. In additional to the graphical interface, a
vibration alarm is raised when a decision point is reached. A screenshot of the AR-
based prototype is given in Fig. 11.2 .