The Overlay Layers task combines two or more layers into a single layer. You can think of overlay as peering through a stack of maps and creating a single map containing all the information from the stack. Before the advent of GIS, cartographers would manually copy maps onto clear acetate sheets, overlay the sheets on a light table, and hand draw a new map from the overlaid data. Overlay is more than a merging of line work; all the attributes of the features in the overlay are carried through to the final product. Overlay is used to answer one of the most basic questions of geography: What is on top of what?
The following are examples:
http://<analysis url>/OverlayLayers/submitJobinputLayer
(Required)
The point, line, or polygon features that will be overlayed with the overlayLayer parameter.
Syntax: As described in detail in the Feature input topic, this parameter can be one of the following:
Examples:
overlayLayer
(Required)
The features that will be overlaid with the inputLayer parameter features.
Syntax: As described in detail in the Feature input topic, this parameter can be one of the following:
Examples:
overlayType
The type of overlay to be performed.
Values: Intersect | Union | Erase
Intersect
Computes a geometric intersection of the input layers. Features or portions of features that overlap in both the inputLayer and overlayLayer parameters will be written to the output layer. This is the default.
Union
Computes a geometric union of the input layers. All features and their attributes will be written to the output layer. This option is only valid if both the inputLayer and the overlayLayer parameter values contain polygon features.
Erase
Only those features or portions of features in the inputLayer parameter that do not overlap the features in the overlayLayer parameter are written to the output.
Example: "overlayType": "Union"
outputType
The type of intersection to be found. This parameter is only valid when the overlayType parameter value is Intersect.
Values: Input | Line | Point
snapToInput
A Boolean value indicating whether feature vertices in the inputLayer parameter are allowed to move. The default is false and means if the distance between features is less than the tolerance value, all features from both layers can move to allow snapping to each other. When set to true, only features in overlayLayer can move to snap to the inputLayer features.
Values: true | false
Example: "snapToInput": true
tolerance
A double value of the minimum distance separating all feature coordinates as well as the distance a coordinate can move in the X or Y (or both) direction. The tolerance units are the same as the inputLayer units.
outputName
If provided, the task will create a feature service of the results. You define the name of the service. If an outputName value is not provided, the task will return a feature collection.
Syntax:
{
"serviceProperties": {
"name": "<service name>"
}
}Syntax:
{
"itemProperties": {
"itemId": "<itemID of the existing feature service>",
"overwrite": true
}
}{
"serviceProperties": {
"name": "<existing service name>"
},
"itemProperties": {
"itemId": "<itemID of the existing feature service>",
"overwrite": true
}
}context
The Context parameter contains the following additional settings that affect task operation:
Syntax:
{
"extent" : {extent},
"outSR" : {spatial reference}
}f
The response format. The default response format is html.
Values: html | json
ResponseWhen 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 the jobId value to periodically check the status of the job and messages as described in Checking job status. Once the job has successfully completed, use jobId to retrieve the results. To track the status, you can make a request of the following form:
http://<analysis url>/OverlayLayers/jobs/<jobId>When the status of the job request is esriJobSucceded, you can access the results of the analysis by making a request of the following form:
http://<analysis url>/OverlayLayers/jobs/<jobId>/results/outputLayer?token=<your token>&f=jsonoutputLayer
The features that are the result of the overlay. The type of feature (point, line, or polygon) depends on the input parameter settings.
Example:
{"url":
"http://<analysis url>/OverlayLayers/jobs/<jobId>/results/outputLayer"}The result includes properties for parameter name, data type, and value. The contents of value depend on the outputName parameter provided in the initial request.
{
"paramName":"outputLayer",
"dataType":"GPString",
"value":{"url":"<hosted featureservice layer url>"}
}{
"paramName":"outputLayer",
"dataType":"GPString",
"value":{"layerDefinition": {}, "featureSet": {} }
}See Feature Output for more information about how the result layer or collection is accessed.
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