An important feature of EasyTracker is its ability to
choose among various maps (Google Maps, Open Street
Map and Microsoft Bing Maps), also the possibility to use
offline maps. The latter is very important when the user is
currently in an area that has no network or a bad connection.
Fig. 2 illustrates two screenshots of the application.
Departing from the features that are more or less
available in many other similar applications, to protect users’
privacy the application allows registering user-defined areas
inside where recording is not permitted. Such an area is
defined by a point (either set manually by providing exact
coordinates or by touching on the map) along with a desired
radius around this point and a characteristic name (e.g. home,
work, mam’s house). The user can specify up to five privacy
locations using a radius which is limited from 15 meter till
300 kilometers. Fig. 3 depicts screenshots of this privacy
filter.
B. Compressing incoming GPS feed
One of the differences between conventional GPSTrackers
and EasyTracker is the exploitation of several
state-of-art algorithms which are responsible to decide
which GPS recordings to be saved in the stored trajectory so
as to minimize the mobile device’s storage cost.
EasyTracker incorporates four spatiotemporal compression
techniques for this purpose: algorithms to save a track to a
local data base: Minimal Time / Minimal Distance Method,
which is a component part of the Android SDK [16], Before
Opening Window (BOPW) [17], Normal Opening Window
(NOPW) [17] and Threshold Algorithm [18]. (The detailed
presentation of the above methods is omitted due to space
limitations.)
To demonstrate the results of compression achieved by
the above methods, we use the path illustrated in Fig. 4.