Start tracking
This section guides you through building a tracking application that captures device locations.
Create a tracker
Create a tracker resource to store and process position updates from your devices. You can use the Amazon Location Service console, the AWS CLI, or the Amazon Location APIs.
Each position update stored in your tracker resources can include a measure of position accuracy, and up to three fields of metadata about the position or device that you want to store. The metadata is stored as key-value pairs, and can store information such as speed, direction, tire pressure, or engine temperature.
Trackers filter position updates as they are received. This reduces visual noise in your device paths (called jitter), and reduces the number of false geofence entry and exit events. This also helps manage costs by reducing the number of geofence evaluations initiated.
Trackers offer three position filtering options to help manage costs and reduce jitter in your location updates.
-
Accuracy-based – Use with any device that provides an accuracy measurement. Most mobile devices provide this information. The accuracy of each position measurement is affected by many environmental factors, including GPS satellite reception, landscape, and the proximity of Wi-Fi and Bluetooth devices. Most devices, including most mobile devices, can provide an estimate of the accuracy of the measurement along with the measurement. With
AccuracyBasedfiltering, Amazon Location ignores location updates if the device moved less than the measured accuracy. For example, if two consecutive updates from a device have an accuracy range of 5 m and 10 m, Amazon Location ignores the second update if the device has moved less than 15 m. Amazon Location neither evaluates ignored updates against geofences, nor stores them.When accuracy is not provided, it is treated as zero, and the measurement is considered perfectly accurate.
Note
You can also use accuracy-based filtering to remove all filtering. If you select accuracy-based filtering, but override all accuracy data to zero, or omit the accuracy entirely, then Amazon Location will not filter out any updates.
-
Distance-based – Use when your devices do not provide an accuracy measurement, but you still want to take advantage of filtering to reduce jitter and manage costs.
DistanceBasedfiltering ignores location updates in which devices have moved less than 30 m (98.4 ft). When you useDistanceBasedposition filtering, Amazon Location neither evaluates these ignored updates against geofences nor stores the updates.The accuracy of most mobile devices, including the average accuracy of iOS and Android devices, is within 15 m. In most applications,
DistanceBasedfiltering can reduce the effect of location inaccuracies when displaying device trajectory on a map, and the bouncing effect of multiple consecutive entry and exit events when devices are near the border of a geofence. It can also help reduce the cost of your application, by making fewer calls to evaluate against linked geofences or retrieve device positions. -
Time-based – (default) Use when your devices send position updates very frequently (more than once every 30 seconds), and you want to achieve near real-time geofence evaluations without storing every update. In
TimeBasedfiltering, every location update is evaluated against linked geofence collections, but not every location update is stored. If your update frequency is more often than 30 seconds, only one update per 30 seconds is stored for each unique device ID.
Note
Be mindful of the costs of your tracking application when deciding your filtering method and the frequency of position updates. You are billed for every location update and once for evaluating the position update against each linked geofence collection. For example, when using time-based filtering, if your tracker is linked to two geofence collections, every position update will count as one location update request and two geofence collection evaluations. If you are reporting position updates every 5 seconds for your devices and using time-based filtering, you will be billed for 720 location updates and 1,440 geofence evaluations per hour for each device.
Your bill is not affected by the number of geofences in each collection. Since each geofence collection may contain up to 50,000 geofences, you may want to combine your geofences into fewer collections, where possible, to reduce your cost of geofence evaluations.
By default, you will get EventBridge events each time a tracked device enters or exits a linked geofence. For more information, see Link a tracker to a geofence collection.
You can enable events for all filtered position updates for a tracker resource. For more information, see Enable update events for a tracker.
Note
If you wish to encrypt your data using your own AWS KMS customer managed key, then the Bounding Polygon Queries feature will be disabled by default. This is because by using this Bounding Polygon Queries feature, a representation of your device positions will not be encrypted using the your AWS KMS managed key. However, the exact device position is still encrypted using your managed key.
You can choose to opt-in to the Bounding Polygon Queries feature by setting the KmsKeyEnableGeospatialQueries parameter to true when creating or updating a Tracker.
Note
Billing depends on your usage. You may incur fees for the use of other AWS
services. For more information, see Amazon Location Service
pricing
You can edit the Description, Position filtering, and EventBridge configuration after the tracker is created by choosing Edit tracker.
Authenticating your requests
Once you create a tracker resource and you're ready to begin evaluating device positions against geofences, choose how you would authenticate your requests:
-
To explore ways you can access the services, see Accessing Amazon Location Service.
-
If you want to publish device positions with unauthenticated requests,you may want to use Amazon Cognito.
Example
The following example shows using an Amazon Cognito identity pool for authorization, using AWS JavaScript SDK v3
, and the Amazon Location Authentication helpers. import { LocationClient, BatchUpdateDevicePositionCommand } from "@aws-sdk/client-location"; import { withIdentityPoolId } from "@aws/amazon-location-utilities-auth-helper"; // Unauthenticated identity pool you created const identityPoolId = "us-east-1:1234abcd-5678-9012-abcd-sample-id"; // Create an authentication helper instance using credentials from Cognito const authHelper = await withIdentityPoolId(identityPoolId); const client = new LocationClient({ region: "us-east-1", // The region containing both the identity pool and tracker resource ...authHelper.getLocationClientConfig(), // Provides configuration required to make requests to Amazon Location }); const input = { TrackerName: "ExampleTracker", Updates: [ { DeviceId: "ExampleDevice-1", Position: [-123.4567, 45.6789], SampleTime: "2020-10-02T19:09:07.327Z", }, { DeviceId: "ExampleDevice-2", Position: [-123.123, 45.123], SampleTime: "2020-10-02T19:10:32Z", }, ], }; const command = new BatchUpdateDevicePositionCommand(input); // Send device position updates const response = await client.send(command);
Update your tracker with a device position
To track your devices, you can post device position updates to your tracker. You can later retrieve these device positions or the device position history from your tracker resource.
Each position update must include the device ID, a timestamp , and a position. You may optionally include other metadata, including accuracy and up to 3 key-value pairs for your own use.
If your tracker is linked to one or more geofence collections, updates will be
evaluated against those geofences (following the filtering rules that you specified
for the tracker). If a device breaches a geofenced area (by moving from inside the
area to outside, or vice versa), you will receive events in EventBridge. These
ENTER or EXIT events include the position update
details, including the device ID, the timestamp, and any associated metadata.
Note
For more information about position filtering, see Create a tracker.
For more information about geofence events, see Reacting to Amazon Location Service events with Amazon EventBridge.
Use either of these methods to send device updates:
-
Send MQTT updates to an AWS IoT Core resource and link it to your tracker resource.
-
Send location updates using the Amazon Location Trackers API, by using the AWS CLI, or the Amazon Location APIs. You can use the AWS SDKs to call the APIs from your iOS or Android application.
Get a device's location history from a tracker
Your Amazon Location tracker resource maintains the location history of all your tracked devices for a period of 30 days. You can retrieve device location history, including all associated metadata, from your tracker resource. The following examples use the AWS CLI, or the Amazon Location APIs.
List your device positions
You can view a list device positions for a tracker using the AWS CLI, or the
Amazon Location APIs, with the ListDevicePositions API.
When you call the ListDevicePositions API, a list of the latest positions for all
devices associated with a given tracker is returned. By default this API returns 100 of the latest
device positions per page of results for a given tracker.
To only return devices within a specific region use the FilterGeometry parameter
to create a Bounding Polygon Query.
This way when you call ListDevicePositions, only devices inside the polygon will be returned.
Note
If you wish to encrypt your data using your own AWS KMS customer managed key, then the Bounding Polygon Queries feature will be disabled by default. This is because by using this feature, a representation of your device positions will not be encrypted using the your AWS KMS managed key. The exact device position, however; is still encrypted using your managed key.
You can choose to opt-in to the Bounding Polygon Queries feature. This is done by setting the KmsKeyEnableGeospatialQueries parameter to true when creating or updating a Tracker.
