Find Nearest Road
ISYS Find Nearest Road converts a location expressed as a Latitude/Longitude or Grid reference to
the name of the road and address (if relevant) of the location. Commonly known as reverse geo-coding.
This module uses a vehicles Latitude/Longitude location and direction of travel (if known) to compute
precisely which road a vehicle is on.
ISYS Know-How
Even with a 100% accurate vehicle location, vehicle direction is still necessary
to determine which road a vehicle is on.
The majority of the map databases from Ordnance Survey and all the map databases from
other suppliers (e.g. Navteq, TeleAtlas) contain road centreline coordinates, not road edge
coordinates. In addition, coordinates for side roads are 'extended' so as to join the
centre-line of the roads they intersect.
A vehicle travelling down a road will generally be to one side of the road
centre-line and will cross these side road 'extensions' at every intersection. If the
vehicle direction is not taken into account and you simply choose the ‘closest’ road to
a vehicle location, then, in the vicinity of road intersections a side road 'extension'
will invariably be closer.
By using the vehicle direction and comparing it to the road direction, it is possible to
eliminate side roads as possibilities and correctly identify the road a vehicle is on.