Electronic horizon
Mapbox Electronic Horizon is a feature of the Mapbox Navigation SDK that surfaces map data along the probable path (or paths) of a vehicle within the road network to anticipate conditions beyond the physical "visible" horizon. The data provided by the electronic horizon enables capabilities like adaptive cruise control, proactive driver alerts for upcoming congestion, speed change and dangerous curves, and available alternative paths. Mapbox Electronic Horizon is designed for Advanced Driver Assistance Systems (ADAS) for in-vehicle deployment, but it can also be used in mobile iOS applications.
The Mapbox Electronic Horizon feature of the Mapbox Navigation SDK is in public beta and is subject to changes, including its pricing. Use of the feature is subject to the beta product restrictions in the Mapbox Terms of Service.
Mapbox reserves the right to end any free tier or free evaluation offers at any time and requires customers to place an order to purchase the Mapbox Electronic Horizon feature, regardless of the level of use of the feature.
Turn-by-turn and free-drive navigation
The Mapbox Navigation SDK allows users to navigate in two different modes: turn-by-turn and free-drive navigation. The electronic horizon feature works in both modes.
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During turn-by-turn navigation (also called active navigation), the user-selected route and its metadata are used as the path for the electronic horizon.
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During free-drive navigation (also called passive navigation), the electronic horizon will determine the most probable path from the vehicle's current location.
For both turn-by-turn and free-drive navigation, the electronic horizon and its metadata are exposed via the same interface in the Navigation SDK as described below.
Configuring electronic horizon detection
Initialize an ElectronicHorizonConfig object to configure electronic horizon detection. Then set it to CoreConfig.electronicHorizonConfig to start electronic horizon updates.
var coreConfig = CoreConfig()
coreConfig.electronicHorizonConfig = ElectronicHorizonConfig(
length: 500,
expansionLevel: 1,
branchLength: 50,
minTimeDeltaBetweenUpdates: nil
)
return MapboxNavigationProvider(coreConfig: coreConfig)
To begin receiving electronic horizon updates, set up observers of electronic horizon–related events and start the updates by calling startupdatingehorizon().
let electronicHorizonController = mapboxNavigationProvider.electronicHorizon()
electronicHorizonController.startUpdatingEHorizon()
Electronic horizon notifications are only fired when the trip session is started and external resources, navigation tiles, are downloaded, so notifications might not fire right away.
Most probable path
Mapbox Electronic Horizon represents the road network ahead of the user as a tree of edges. For example, an edge may represent a road segment between two intersections or between the two ends of a bridge. An edge may traverse multiple road objects, and a road object may be associated with multiple edges. Each intersection has outlet edges, representing a connecting road segment with a calculated probability that the user will transition to it.
Based on the device's location and user-selected route (if applicable), Mapbox Electronic Horizon determines the most likely path a user may take and provides a most probable path (MPP). The MPP contains data in a tree-like structure where edges have a level attribute equal to 0 and side-branches have a level attribute equal to 1 or higher based on their position relative to the current edge.
In most cases, the electronic horizon will return one MPP, but if two or more alternatives at an intersection have a similar probability (a difference less or equal to 5%), the electronic horizon might return several MPP paths. You can choose the MPP with a slightly higher probability or, if you have additional information about the road conditions, you can suggest which MPP the user should choose.
Observing position events
To find out when the electronic horizon or MPP changes due to a user location update, subscribe to eHorizonEvents notifications.
electronicHorizonController.eHorizonEvents
.compactMap { $0.event as? EHorizonStatus.Events.PositionUpdated }
.sink { [weak self] event in
self?.handle(positionUpdatedEvent: event)
}.store(in: &subscriptions)
The EHorizonStatus.Events.PositionUpdated contains the electronic horizon edge structure in startingEdge and the user’s position in the routing graph in position.
startingEdge is set to an RoadGraph.Edge object, which is a starting point in a tree of edges that you can traverse recursively to explore the routing graph in the vicinity of the user.
Get more details about an edge
To get more details about an edge, such as its name and shape, get the active RoadGraph object from the RoadMatching.roadGraph, then pass the edge’s identifier into the RoadGraph object’s methods.
Demonstrates how to use electronic horizon to predict the user's most probable path and show upcoming intersections.
Road objects
Road objects represent routing-related landmarks within the routing graph, such as traffic incidents, tunnel entrances, and border crossings.
Observing road object notifications
To find out when the user enters or exits the geofence associated with a road object, observe the EHorizonStatus.Events.RoadObjectEntered and EHorizonStatus.Events.RoadObjectExited events, respectively.
func startUpdatingRoadObjects() {
electronicHorizonController.eHorizonEvents
.compactMap {
switch $0.event {
case let event as EHorizonStatus.Events.RoadObjectEntered:
return event.roadObjectId
case let event as EHorizonStatus.Events.RoadObjectExited:
return event.roadObjectId
default:
return nil
}
}
.sink { [weak self] roadObjectId in
self?.handleEnterOrExit(roadObjectId: roadObjectId)
}.store(in: &subscriptions)
electronicHorizonController.startUpdatingEHorizon()
}
Get more details about a road object
To get more details about a road object, such as its location and type, get the active RoadObjectsStore object from the RoadMatching.roadObjectStore, then pass the road object identifier into the RoadObjectsStore object’s methods.