In-car navigation devices – those moving maps on a dashboard LCD screen that help guide you over unfamiliar roads - are made possible by a space-age technology called GPS or the Global Positioning System.
Operated by the US Government, GPS consists of an array of satellites – currently 31 – orbiting around the globe at an altitude of approximately 20,200 kilometres. These GPS satellites broadcast signals on a regular basis that are picked up by the GPS receiver. If the receiver can access signals from three satellites simultaneously, the GPS unit can calculate your exact location. In-car navigation plots your GPS-based location on a digital street map to accurately depict your location on the map and provide visual and spoken directions to your destination.
The key issue for in-car navigation vendors is the digital street map that provides the context for your GPS location. In order for the in-car navigation device to work correctly, the digital street map must be accurate in respect to the exact location of the street centreline; it must be complete, especially with new subdivisions; and it must be accurate in respect to things like one-way streets, turn restrictions, barriers, etc. Some digital street maps include points of interest like speed camera locations, crash black spots and red light cameras.
The TomTom products use the SmartNAV digital database sourced from GeoSmart (www.geosmart.co.nz), the leading Kiwi-owned and operated spatial mapping organisation. GeoSmart have driven over 94,000 km of public roads in New Zealand collecting a large range of road attributes including correct road names, turn restrictions (one way streets as well as no left turn, no right turn etc), speed zones, paving, angles of corners (to assist in travel time calculation when the speed limit is faster than realistic driving speeds), type and angles of intersections, intersection controls and much more. GeoSmart continues to drive and collect data as new roads and subdivisions are built and when roads are modified.
Uniden sources digital base maps from Sensis, a multi-national air defense, air traffic control, airline and airport operations management and data integration and distribution firm. Sensis maps are sourced from Terralink (www.terralink.co.nz). They cover the whole of New Zealand, encompassing 147,611 km of navigable roads and 78,982 km with address number ranges. This reaches >99% of the population. Sensis provides 92,000 points of interest in 66 categories including petrol stations. Turn restrictions are included with road attributes. Uniden supplements this information with their own data which currently includes speed cameras, red light cameras and black spots.
The Laser Navig8tr in-car navigation units will be using digital street maps containing information covering the whole country. The digital data bases include all streets, motorways, one way systems, country roads and road restrictions. For point of interest information, Laser will show fixed speed cameras locations with voice warnings as well as petrol stations, ATMs, schools and hotels. Contextual information includes forests, parks, rivers etc. The digital base map will be updated annually.
In car navigation has proven especially popular in Europe where they have zillions of roads and signage of variable quality. Purchasing individual street maps for, say, Belgium or France would be prohibitively expensive. In-car navigation is also popular in America for the same reasons. While in-car navigation is relatively new to the New Zealand market, there is a tremendous potential, especially in light of the excellent digital street maps available.
In-car navigation can be helpful for a number of user types. For tourists or people in rental cars, unfamiliar with the landscape, an in-car navigation unit can be handy. Also for delivery people or others who need to go to individual addresses over a large area. A benefit of in-car navigation is that you don’t need to be constantly looking for street signs; also if you do get lost, a GPS unit can help you get your bearings and put you back on the right track. Additionally, the GPS units can display ancillary information which is useful, such as petrol stations, speed cameras and other landmarks. An advantage of portable in-car navigation units is that, if indeed you go overseas, you can add local maps and use the units in the same manner as here in NZ.
GPS can provide locational accuracy within millimetres – surveyors almost exclusively use GPS-enhanced theodolites for field work - works night or day, rain or shine and is extremely cost-effective. Since the disablement of Selective Availability (a random error introduced by the US government to hinder hostile powers from using GPS data) in 1991, the uptake of GPS technology for other applications has been phenomenal. In NZ, GPS is a key input into GIS (geographic information systems) and is used extensively by local councils, central government, agriculture and the transport sectors. Mapmakers make extensive use of GPS technology while hand-held GPS units are popular with trampers, boaters and others who need to know their exact location.
Q:
How accurate is GPS and in-car navigation devices?
A:
Accuracy is a relative term. GPS locational data can be extremely accurate, within a few centimetres. The accuracy of the digital street base map, on the other hand, can have varying degrees of accuracy, typically in how up-to-date it is. For instance, road closures, new roads in sub-divisions, private roads and other factors might not be present on your GPS unit. Best to rely on the in-car navigation unit as a helpful guide and not as 100% accurate all the time.
Q:
Can in-car navigation units distract a person when driving?
A:
Yes. Like talking on a mobile phone, tuning the radio or even reading a paper-based road map, GPS units can be distracting if you are behind the wheel. In-car navigation units try to make the information quickly accessible at a glance. However, if you have to interact with the unit – such as changing your destination - it is best to pull over.
Q:
A:
Yes. The digital mapping companies that provide the digital base maps are constantly updating the roads and features on the maps. Update costs and availability vary with the products. User feedback is especially appreciated. As the technology gains in popularity, map vendors will add even more features to their maps such as attractions, historical sites, hotels, restaurants and the like. With products like Google Maps, one day you’ll able to add your own features to the digital map base and incorporate it into your in-car navigation unit.
Copyright © 2009 Elmbrook Technologies Limited. Software Graphics Website Design