- URL:
- https://<root>/System/RasterAnalysisTools/GPServer/AnalyzeChangesUsingLandTrendr
- Methods:
GET
- Version Introduced:
- 10.9
Description
The Analyze
task evaluates changes in pixel values over time using the Landsat based detection of trends in disturbance and recovery (LandTrendr) method and generates a change analysis raster containing the model results.
Request parameters
Parameter | Details |
---|---|
(Required) | The portal item ID, image service URL, cloud multidimensional raster dataset or shared multidimensional raster dataset. At least one type of input needs to be provided in the JSON object. If multiple inputs are given, the Syntax: A JSON object describes the input multidimensional raster. Example:
|
(Required) | Output hosted image service properties. If the hosted image service is already created, the portal item ID or service URL can be provided, and the output path of the multidimensional raster dataset generated in the raster store will be used to update the existing service definition. The service tool can also generate a new hosted image service with the given service properties. Syntax: String Example:
|
(Optional) | The name of the band to use for segmenting pixel value trajectories over time. Choose the band that will best capture the changes in the feature you want to observe. If no band name is specified and the input is multiband imagery, the first band from the input multiband imagery will be used. Syntax: String Example:
|
(Optional) | The date used to select a slice for each year in the input multidimensional dataset. The slice with the date closest to the snapping date will be selected. This parameter is required if the input dataset contains sub-yearly data, since this tool only processes one slice per year. The default is Syntax: String, in the format of Example:
|
(Optional) | The maximum number of segments to be fitted to the time series for each pixel. The default is 5. Syntax: Long integer. Example:
|
(Optional) | The number of additional vertices beyond Syntax: Long integer. Example:
|
(Optional) | The threshold to use for dampening anomalies in the pixel value trajectory. The value must range between 0 and 1, where 1 means no dampening. The default is 0.9. Syntax: Double Example:
|
(Optional) | The recovery threshold value in years. If a segment has a recovery rate that is faster than Syntax: Double Example:
|
(Optional) | Specifies whether segments that exhibit a one-year recovery will be excluded. When set to Values: |
(Optional) | Specifies whether recovery from change is represented by an increasing (positive) trend. When set to Values: |
(Optional) | The minimum number of valid observations required to perform fitting. The number of years in the input multidimensional dataset must be equal to or greater than this value. The default is 6. Syntax: Long Example:
|
(Optional) | The best model proportion value. During the model selection process, the tool will calculate the p-value for each model and select a model that has the most vertices while maintaining the smallest (most significant) p-value based on this proportion value. A value of 1 means the model has the lowest p-value but may not have a high number of vertices. The default is 1.25. Syntax: Double Example:
|
(Optional) | The p-value threshold to be reached for a model to be selected. After the vertices are detected in the initial stage of the model fitting, the tool will fit each segment and calculate the p-value to determine the significance of the model. On the next iteration, the model will decrease the number of segments by one and recalculate the p-value. This will continue and, if the p-value is smaller than the value specified in this parameter, the model will be selected and the tool will stop searching for a better model. If no such model is selected, the tool will select a model with a p-value smaller than the lowest p-value × best model proportion value. The default is 0.01. Syntax: Double Example:
|
(Optional) | Specifies whether other bands will be included in the segmentation process. When set to Values: |
| Contains additional settings that affect task execution. This task has the following settings:
Example:
|
| The response format. The default response format is Values: |
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 job
to periodically check the status of the job and messages, as described in Checking job status. Once the job has successfully completed, use the job
to retrieve the results. To track the status, you can make a request of the following form:
https://<analysis-url>/AnalyzeChangesUsingLandTrendr/jobs/<jobId>
Accessing 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://<raster analysis url>/AnalyzeChangesUsingLandTrendr/jobs/<jobId>/results/outputAnalysisRaster?token=<your token>&f=json
Parameter | Details |
---|---|
| The output multidimensional raster Example:
The result has properties for parameter name, data type, and value. The content of the value is always the output raster dataset's
|