ROs RealObjects - Programming GPS and OpenStreetMap Applications with Java - page 67

Part III
ROs - RealObject s
Parts I and II provided the prerequisites to grasp the project vision as well
as a feeling for the object-oriented programming approach. The GPS unit
and the map panel encapsulate domain knowledge and provide developer
tools as a common basis.
This part implements RealObject s as the root class for all real-world
objects interacting in real-world scenarios. In the real world, a physical
object is any thing with mass, size (shape), and a location (orientation) at
any point in time. In the computer world, every (real) object is a program
of its own, an entity with an internal behavior and interfaces connecting it
to external environments.
In order to reflect realistic motion, the platonic RealObject will be en-
abled to replay a GPS trace recorded in the real world. Before a RealObject
can simulate real motion it has to be enabled to read a digital map and
move along its network of roads.
The processing of digital maps for cartography and navigation is de-
scribed in detail. We make use of the freely available digital map source
OpenStreetMap ( www.openstreetmap.net ). With preprocessed digital map
data for a dedicated area, each RealObject can be equipped with a navi-
gation system to read the map and make a decision on which direction to
take.