- URL:
- https://<geoanalytics-url>/SnapTracks
- Methods:
GET
- Version Introduced:
- 11.0
Description
The Snap
task matches track points to polylines and requires the following input layers:
-
point
—The input point layer must be time-enabled observations that represent an instant in time. Track observations that do not have a valid time stamp will be excluded from analysis.Layer -
polyline
—The input polyline layer must contain fields with the following connectivity information and must be specified in theLayer connectivity
parameter:Field Matching polyline
—The unique identifier for the polylineID from
—The node where a polyline beginsNode ID to
—The node where a polyline endsNode ID
From nodes and to nodes indicate how each polyline is connected, and how they can be traversed by the input points.
The spatial reference of the input
must be the same as the spatial reference of the input
. If the datasets have different spatial references, specify an output coordinate system or project for the datasets prior to analysis.
Snap
determines which point features belong to a track using an identifier. Using the time at each location, the tracks are ordered sequentially and analyzed to find the polyline feature they match.
For example, you have GPS measurements of delivery vehicles every 30 seconds. Each GPS measurement records the vehicle ID, location, and time. You can match the GPS points to polylines to more accurately determine which areas delivery trucks are servicing and which locations could have more delivery resources allocated.
The following table outlines terminology used in the Snap
task:
Term | Description |
---|---|
Track | A sequence of features that are time-enabled with time type instant. Features are determined to be in sequence using a track identifier field and their order in time. For example, a city could have a fleet of snow plow trucks that record their location every 30 seconds. The vehicle ID could represent the distinct tracks. |
Observation | A point in a track. |
Node | The end vertices of polyline features used to indicate the direction of the polyline. The start of the polyline is the from node and the end of the polyline is the to node. |
Direction | The direction of a polyline. Direction refers to how a polyline can be travelled between the from node and to node. |
Connectivity | Connectivity describes how polylines are connected to represent a traversable network. Polylines are connected based on their from node and to node values. Polylines that cannot be reached by a point, based on connectivity, will not be considered a match. |
Traversable | Polylines are traversable if they are connected by common nodes. For example, if the from node of polyline A is the same as the to node for polyline B, they are traversable. |
Request parameters
Parameter | Details |
---|---|
| The track point features that will be matched to polylines. Syntax: As described in Feature input, this parameter can be one of the following:
REST examples
|
| The polyline features to which track points will be matched. Syntax: As described in Feature input, this parameter can be one of the following:
REST examples
|
| The fields used to identify distinct tracks. There can be multiple REST examples
|
| One or more fields from the REST examples
|
| The polyline layer fields that will be used to define the connectivity of the input polyline features. The following values are required:
REST examples
|
| The polyline layer field and attribute values that will be used to define the direction of the input polyline features. For example, a polyline layer has a field named REST examples
|
| The maximum distance allowed between a point and any polyline to be considered a match. It is recommended that you use values less than or equal to 50 meters. Larger distances will result in a longer process time and less accurate results. REST examples
|
| The REST examples
|
| The method used to calculate search distances between points and lines. There are two methods: REST examples
|
| Specifies whether all input features are returned or only the input features that were matched to a line feature. REST examples
|
| A time duration used to split tracks. Any features in the REST examples
|
| The temporal unit to be used with the temporal distance value specified in Values: REST examples
|
| A distance used to split tracks. Any features in the REST examples
|
| The distance unit to be used with the distance value specified in Values: REST examples
|
|
A time boundary allows you to analyze values within a defined time span. For example, if you use a time boundary of 1 day, starting on January 1, 1980, tracks will be analyzed one day at a time. REST examples
|
|
The unit applied to the time boundary. Values: REST examples
|
|
A date that specifies the reference time to align the time boundary to, represented in milliseconds from epoch. The default is January 1, 1970, at 12:00 a.m. (epoch time stamp 0). This option is only available if the REST examples
|
|
The task will create a feature service of the results. You define the name of the service. REST examples
|
|
The
Syntax:
|
|
The response format. The default response format is Values: |
Example usage
The following is a sample request URL for Snap
:
https://machine.domain.com/webadaptor/rest/services/System/GeoAnalyticsTools/GPServer/SnapTracks/submitJob?pointLayer={"url":"https://webadaptor.domain.com/server/rest/services/DeliveryTracks/0"}&polylineLayer={"url":"https://webadaptor.domain.com/server/rest/services/Roads/0"}&trackFields=TruckID&polylineFieldsToInclude=Street,Speed&connectivityFieldMatching={"polylineId":"streetname","fromNode":"fromnodeid","toNode":"tonodeid"}&directionFieldMatching={"directionField":"dirtravel","forwardValue":"F","backwardValue":"T","noneValue":"","bothValue":"B"}&searchDistance=5&searchDistanceUnit=Meters&distanceMethod=Geodesic&outputName=myOutput&context={"extent":{"xmin":-122.68,"ymin":45.53,"xmax":-122.45,"ymax":45.6,"spatialReference":{"wkid":4326}}}&f=json
Response
When you submit a request, the service assigns a unique job ID for the transaction.
Syntax:
{
"jobId": "<unique job identifier>",
"jobStatus": "<job status>"
}
After the initial request is submitted, you can use job
to periodically check the status of the job and messages as described in Check job status. Once the job has successfully completed, use job
to retrieve the results. To track the status, you can make a request of the following form:
https://<analysis url>/SnapTracks/jobs/<jobId>
Access results
When the status of the job request is esri
, you can access the results of the analysis by making a request of the following form:
https://<analysis-url>/SnapTracks/jobs/<jobId>/results/output?token=<your token>&f=json
Response | Description |
---|---|
| The
The result has properties for parameter name, data type, and value. The contents of
See Feature output for more information about how the result layer is accessed. |