Feature Layer Attributes

Characteristic

Short description

A Feature Layer (for example: PTV_TruckAttributes) defines a set of road attributes which decisively affect routeA route corresponds to a path of a vehicle through the underlying transport network. The main attributes of a route are the distance and the time that the vehicle travels along the path. planning. These features can be relevant for routing in general or only under particular conditions, whereby vehicleThe term vehicle describes what is being routed or planned for. Vehicles are used in route calculation, distance matrix calculation and effectively also in tour planning. In route calculation, vehicle properties like overall size, weight and speed are in focus. In tour planning, it is vehicle properties like capacity and availability. Commonly a vehicle is motorized, like a truck - including its trailer or a car. However also a bike or even a pedestrian are included in this definition.- or time-dependency are possible conditions.

Use

Main use case are route and tour calculations with optional consideration of used vehicle and traveling time.

Detailed Consideration

Feature Layer attributes, or simply called features, define different particular actions which are applied when a route is calculated or a map is drawn. A typical example represents the closure of a road for all vehicles. In xRoute the corresponding road cannot be part of the route, in xMap it is drawn with a dedicated traffic sign.

When the actions of a feature are applied, the feature is said to be relevant. Such a feature can be relevant in common or may depend on some additional conditions. Four main types of features are distinguished concerning their relevance:

As a result, the relevance of a feature may depend on the following context parameters:

Restrictions according vehicle properties

Based on these definitions, a feature is called vehicle-dependent, if it is only relevant with respect to a particular vehicle profileA profile is a collection of parameters used to configure the request. Full profiles consist of a number of specialized sub-profiles like the VehicleProfile which describes the properties of a vehicle.. Vehicle-independent features are always relevant, whatever the specified vehicle is. If the vehicle is not specified, all vehicle-dependent features are relevant.

Restrictions according time consideration

A feature is called time-dependent, if its relevance depends on a time domain, for example only certain days of a week, or for a certain span of day time. A reference time is available for each point along the course of a route, so each time domain can be compared to this reference time. The reference time may vary according the time consideration scenario:

Time consideration scenario Feature is relevant
No time consideration if feature is not time restricted
snapshot time consideration (referenceTime) if feature is not time restricted or feature's time domain fits a concrete specified reference time
time span consideration (referenceTime, duration) if feature is not time restricted or feature's time domain fits complete time span [time, time + duration]
exact time consideration (referenceTime) if feature is not time restricted or feature's time domain fits specified reference time + travel time til current road.

Features without any time restrictions are always relevant, whatever the specified reference time is.

Relevance at all

A feature is called relevant if it is relevant with respect to a particular vehicle profile and relevant with respect to a particular reference time (and time span).

Rendering

According the specifications mentioned in the previous chapters, there exists three different states for a feature as far as time restrictions are concerned:

The rendering of features helps to emphasize these different modes: Features are rendered according the style defined in the Feature Layer profile. For features which are independent in time, this style is applied directly without any modifications. For time-dependent features, a (predefined and) modified style can be activated via profile parameters, see TimeDependencyStyle. The following table shows how the style for independent features is modified to indicate dependency and its relevance:

Feature is time-dependent Line style Icon style Polygon style
no solid, full-colored unmodified icon fill and contour colored
yes, and relevant dashed, full-colored additional clock, full-colored fill and contour colored
yes, but not relevant dashed, gray additional clock, grayed grayed and hatched

Good to know

Structure of a time-dependent feature

Each single feature is composed of partial information: For a height restriction the height itself has to be specified beside the type of this restriction. All this sub-information is provided as key-value pairs. If a feature is time-dependent, the corresponding GDF time domain and a note, if this feature is relevant according the time consideration settings, is also provided for it. The note is missing if the time domain cannot be evaluated because no referenceTime is defined.

Features with language-dependent content

Features may contain textual information which is available for different languages. For example, a TrafficIncidents feature contains a literal description of the incident. Because the message is only provided for one language, the corresponding language code is added. As a consequence, the original key message is partitioned into message.text and message.language. All key-value pairs for Traffic Incidents Layer can be found in PTV_TrafficIncidents.

Expired features

If the time domain of a feature does not match the time consideration and is totally in the past, so the feature is expired. In this case, it will not be returned in the response. And finally, the expired features will not be displayed on the map.

Hidden features

Features which are time-restricted but not relevant can be hidden instead of grayed using the map option showOnlyRelevantByTime.

Vehicle- and time-dependency in combination with tour optimization

For tour optimization, distance matrices are used providing route information for each combination of the possible waypointsA waypoint is a geographic location used to specify start, destination and possible stopovers for a route.. Each distance matrix reflects the driving distances and times for a single vehicle at a specific time. This means that a separate distance matrix is required for each routing profile that is used. Moreover, time-dependency is only useful for optimization scenarios with short road distances since all relations are calculated with the same start or arrival time.

To get an impression of the feature's structure, a traffic incident with all its key-value pairs is shown:

Related Topics

Technical Concept GDF time domains
Technical Concept Time consideration
Technical Concept Feature Layer basics
Showcase Visualize time dependent Feature Layer data
Integration Sample Displaying a traffic situation