6 Glossary ; City Center; Map - Page 71

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6 Glossary 

2D/3D GPS reception 

The GPS receiver uses satellite signals to calculate its (your) position and needs at least four 
signals to give a three-dimensional position, including elevation. Because the satellites are 
moving and because objects can block the signals, your GPS device might not receive four 
signals. If three satellites are available, the receiver can calculate the horizontal GPS position 
but the accuracy is lower and the GPS device does not give you elevation data: only 2D 
reception is possible. 

Active route 

The currently navigated route. Whenever the destination is set, the route is active until you 
delete it, reach your destination or you quit the navigation system. See also: Route.

City Center

The city/town center is not the geometric center of the city/town but an arbitrary point the map 
creators have chosen. In towns and villages, it is usually the most important intersection; in 
larger cities, it is one of the important intersections. 

Color theme 

The navigation system comes with different color themes for daytime or nighttime use of the 
map and menu screens. Themes are custom graphic settings and they can have different 
colors for streets, blocks or surface waters in 2D and 3D modes, and they display shades or 
shadows in different ways in 3D mode. 
One daytime scheme and one nighttime scheme is always selected for the map and for the menus. 
The navigation system uses them when it switches from day to night and back. 

GPS accuracy 

Several factors have impact on the deviation between your real position and the one given by 
the GPS device. For example, signal delay in the ionosphere or re

fl

 ecting objects near the GPS 

device have a different and varying impact on how accurately the GPS device can calculate 
your position. 

Map 

The navigation system works with digital maps which are not simply the computerized versions 
of traditional paper maps. Similarly to paper road maps, the 2D mode of digital maps show you 
streets, roads, and elevation by colors. 
In 3D mode, you can see the altitude differences, for example valleys and mountains, elevated 
roads, and in selected cities 3D landmarks and 3D buildings are also displayed. 
You can use digital maps interactively: you can zoom in and out (increase or decrease the 
scale), you can tilt them up and down, and rotate them left and right. In GPS-supported 
navigation, digital maps facilitate route planning.