As a next step, the heading and accelerometer data
need to be processed when obtaining a notification
from the Sensor Controller (i.e., the application loop
mentioned in Section 3.1.1 has delivered new data).
Based on this, we can determine whether or not a
POI is located inside the vertical and horizontal field
of view, and at which position it shall be displayed
on the locationView. Recall that the locationView extends
the actual field of view to a larger, orientationindependent
field of view (cf. Fig. 6). The first step is
to determine the boundaries of the locationView based
on sensor data. In this context, the heading data provides
the information required to determine the direction
the device is pointing at. The left boundary
of the locationView can be calculated by determining
the horizontal heading and decreasing it by the half
of the maximal angle of view (cf. Fig. 6). The right
boundary is calculated by adding half of the maximal
angle of view to the current heading. Since POIs have
also a vertical heading, a vertical field of view must
be calculated as well. This is done analogously to the
calculation of the horizontal field of view, except that
the data of the vertical heading is required. Finally,
we obtain a directed, orientation-independent field of
view bounded by left, right, top, and bottom values.
Then we use the vertical and horizontal bearings of a
POI to determine whether it lies inside the location-
View (i.e., inside the field of view). Since we use the
concept of the locationView, we do not have to deal
with the rotation of the device at this point, i.e., we
can normalize calculations to portrait mode since the
rotation itself is handled by the locationView.