figure 6. The prototype of the live-view GPs navigation system.
Position-Aware
Service
orientation-Aware
Service
Amended position,
orientation destination
request for
the planning path
Waypoint-Aware
Service
waypoint lists
Planned path
Waypoint Server
Current position
Augmented
Navigation Service
Trail map
local map
Google map
Server
it should be smaller than the period of
the Unknown state—four seconds in
most cases—set by a conventional GPS
navigating system. Hence, DELTA can
heuristically choose 2 due to the fact
the frequency of GPS receiver receiving
message is 1Hz.
Augmented Navigation Service.
Finally, the LVN system adopts AR service to precisely tag the directional
sign on the captured live video to provide intuitive navigational services.
During the navigation, the system
promptly registers a GPS receiver to
the physical environment first by using the positional data from the position-aware service and the orientation
information from the orientation-aware service. This registration process confirms the spatial relationship
between users and their surrounding
environment. According to the derived
figure 7. user interface for initialization.
(a) list selection and manual input interface
heading waypoint and embrace angle
θ from the waypoint-aware service, the
arrow sign computation algorithm
calculates an appropriate directional
arrow sign to guide the user. Via this
human-centric interactive directional
sign, the system provides an intuitive user interface that enables users
to have adequate time to match their
cognitive maps with navigation maps.
Furthermore, the arrow sign computation algorithm uses a G-sensor to
detect the posture of the user holding
the smartphone and draw the skyline
as well as the directional sign relative
to the screen accordingly. The algorithm is implemented as follows:
1. Calculate the distance from the
current position to user’s heading waypoint;
2. If this distance is beyond a user’s visible range and within a smart-
(b) map’s Pois click interface
phone’s FOV, draw a straight arrow on
the screen that points to the heading
waypoint;
3. If this distance is within a user’s
visible range as well as a smartphone’s
FOV, draw a curvy directional sign
that matches the user’s cognitive map
based on the skyline relative to the
screen, the heading waypoint, and the
embrace angle θ. Notably, angle θ is
computed by the waypoint-aware service; and
4. Otherwise, draw on the screen a
U-turn sign or an arrow sign to the extreme left or right, depending on the
embrace angle θ.
In sum, with the assistance of angle
θ from the waypoint-aware service, the
directional arrow becomes a label that
dynamically points to the heading waypoint in order to provide an intuitive
navigational experience.
application system Prototyping
Effectiveness of the LVN system is
demonstrated by developing a prototyping system as shown in Figure 6.
This system comprises an Android-powered smartphone, a waypoint
server, and a publicly available Google
map server. The waypoint server acts
similar to a gateway server between the
smartphone and the Google Map server. When the smartphone transmits a
user’s current position and destination
to the waypoint server through a 3G
network, the waypoint server then forwards this request to the Google Map
server for a navigational path. Upon
receiving the planned navigation path
from the Google Map server, the way-
