GPS navigation is something that has become very complex, yet millions of consumers everyday make use of the technology. Users take for granted how the technology works, as they expect to only switch on their device and navigate to a point. But how does a navigation company like TomTom gather their data and turn that into a fully-functioning map?
TomTom maps are built in layers containing various types of information. Starting with the base layer, millions of nodes are placed alongside each other containing the Global Positioning System (GPS) co-ordinates of all of the unique points of the area covered.
A next layer of lines are then drawn over these representing the roads, rivers, rails and other geographical features. Next attributes values providing detailed classifications of each individual feature are assigned including the road names, route numbers but also complex information like turn (manoeuvres), speed and vehicle restrictions.
A point of interest or services layer containing e.g. schools and hospitals are then built on top of this followed by the ‘real measured road speeds’ provided by IQ routes and finally TomTom HD Live Traffic services.
The initial data gathered is from satellite and aerial imagery, local authorities and via the mobile field survey workforce, as well as geo-referenced data from the TomTom mobile mapping vans, all contributing to the many factors of the collated information. Community feedback from TomTom consumer devices via the MapShare technology provide input on changes in the real-world which can be verified against reference source material.
One of the main sources of mapping data is collected from the mapping vans. The vans are kitted out with cameras, lidar sensors, gyroscopes, redundant computer systems and very accurate differential GPS. All these devices record their information to a redundant hard disk which provides complete geo-referenced data to the map centre.
The vans are also fitted with sensors on the wheels to determine the distance travelled as well as gyroscopes to record the change in direction of the van providing movement records. This is particularly useful for underground road networks, car parks and other places where GPS signals are challenged.
Back at the map centre, all this information is fed into the inhouse developed Cartopia programme giving the editor an overall life-like view of the surroundings. The cameras capture images every eight metres on city roads and every ten metres on highways with a 360° view of all road signs and roadside features.
All images that are captured are all for internal use only so no privacy issues are involved. Six photos are taken every eight metres which amounts to 750 photos taken every kilometre. With the volume of images that need to be processed, image recognition software is used to select good quality imagery such as road signs and speed limits, which is then automatically applied to the database.
The map editor works with a number of layers to assist with determining the correct mapping information. A basic aerial or satellite image covered by GPS traces from the probe vehicles enables an accurate map to be plotted out, even without a van visiting the location.
This mapping data is used in TomTom’s personal and in-car navigation devices and provides various solutions for different markets such as logistics, banking, telecommunications, insurance, medical, government sectors and defence industries.
Staff writer
