Compute Control Points

Compute Control Points diagram

The ComputeControlPoints operation is a service tool that's used to compute matching control points between images in an image collection and for matching control points between the image collection images and the reference image.

Licensing

License:

As of ArcGIS 10.5, you must license your ArcGIS Server as an ArcGIS Image Server to use this resource.

This operation is supported at 10.6.1 and later.

Request URL

http://<orthomapping service tool url>/ComputeControlPoints/submitJob?
imageCollection={"itemId": "1780d648db3545bba8661ad98df824a4"}&referenceImage={"itemId": 
"1780d648db3545bba8661ad98df824a4"}&imageLocationAccuracy=High&context={}

Request parameters

The following table lists the parameters with syntax and details for each.

ParameterDescription

imageCollection

The image collection (mosaic dataset) name or url.

The image service must exist before calling the service to compute control points.

Syntax: A JSON object supports three keys, itemId, url and uri. These keys are case sensitive.

Example:

{"itemId": “<portal item id>”}
{“url”: “<image service url>”}
{“uri”: “<cloud raster uri or shared data path>”}

referenceImage

(Optional)

The reference image service that can be used to generate ground control points for rectifying the image service.

This setting is optional. If not given, the service tool will compute matching control points among the overlapped images in the image collection.

Example:

{"itemId": “<portal item id>”}
{“url”: “<image service url>”}
{“uri”: “<cloud raster uri or shared data path>”}

imageLocationAccuracy

(Optional)

Allows you to specify the location accuracy of your imagery.

This option allows you to specify the GPS location accuracy level of the source image. It determines how far the tool will search for neighboring matching images for calculating tie points and block adjustments. The following are the available options:

  • High—GPS accuracy of 0 to 10 meters, and the tool uses a maximum of 4 by 3 images.
  • Medium—GPS accuracy of 10 to 20 meters, and the tool uses a maximum of 4 by 6 images.
  • Low—GPS accuracy of 20 to 50 meters, and the tool uses a maximum of 4 by 12 images.
  • VeryLow—GPS accuracy of more than 50 meters, and the tool uses a maximum of 4 by 20 images.

context

(Optional)

Contains additional environment settings that affect the generation of output control points.

{
"pointSimilarity": "MEDIUM",
"pointDensity": "MEDIUM",
"pointDistribution": "RANDOM"
}

Where:

  • pointSimilarity—Sets tolerance for computing control points with varying levels of potential error. The following are the available options:
    • Low tolerance—The similarity tolerance for finding control points will be low. This option will produce the most control points, but some may have a higher level of error.
    • Medium tolerance—The similarity tolerance for finding control points will be medium.
    • High tolerance—The similarity tolerance for finding control points will be high. This option will produce the least number of control points, but each matching pair will have a lower level of error.
  • pointDensity—Sets the number of tie points to be created. The following are the available options:
    • Low—Sets the density of points to be low. This will create the fewest number of tie points.
    • Medium—Sets the density of points to be medium. This will create a moderate number of tie points.
    • High—Sets the density of points to be high. This will create the highest number of tie points.
  • pointDistribution—Creates a set of points with a regular or random distribution. The following are the available options:
    • Random—Randomly generates points that are better for overlapping areas with irregular shapes.
    • Regular—Regularly generates points based on a fixed pattern and uses the point density to determine how frequently to create points.

f

The response format. The default response format is html.

Values: html | json

Response

When you submit a request, the task 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 to periodically check the status of the job and messages as described in Checking job status. Once the job has successfully completed, use the jobId to retrieve the results. To track the status, you can make a request of the following form:

http://<Orthomapping service tool url>/ComputeControlPoints/jobs/<jobId>

Accessing results

When the status of the job request is esriJobSucceeded, you can access the results of the analysis by making a request of the following form:

http://<Orthomapping service tool url>/ComputeControlPoints/jobs/<jobId>/results/result?token=<your token>&f=json

The result will be the control point JSON file.