Mapping Hacks

Route Planning Online #2

Chapter 1, Mapping Your Life

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9

HACK

important to determine whether the navigable feature is located in an urban

area or not. A third characteristic of a navigable feature that can be easily

extracted from the mapping data to provide some further hint for determin-

ing the travel speed is the form of way. This is particularly helpful when it

comes to slip roads (exits) or roundabouts (traffic circles). Although these

traffic situations are part of a particular road class and are situated in the

same area as the connecting navigable features, one typically drives slower in

these conditions than on other road segments. All these attributes of naviga-

ble features are taken into account in assigning travel speeds to navigable

features. The more granular this classification of navigable features is, the

better the route calculation and the more satisfied the user.

Driving Instructions

Once the route between the two locations has been calculated, the driving

directions are presented on screen. At this stage, the output of the route cal-

culation, a sequential list of navigable features, has to be presented in a

human-readable form. Street names and road numbers are the most impor-

tant information and can be easily extracted from the mapping data sets.

You also have to know which turns to take to get from one road into the

next. The angles between two connecting features are used ...