Show viewshed calculated from geoprocessing task

Calculate a viewshed using a geoprocessing service, in this case showing what parts of a landscape are visible from points on mountainous terrain.

Use case

A viewshed is used to highlight what is visible from a given point. A viewshed could be created to show what a hiker might be able to see from a given point at the top of a mountain. Equally, a viewshed could also be created from a point representing the maximum height of a proposed wind turbine to see from what areas the turbine would be visible.

Note: This analysis requires a geoprocessing service endpoint in a connected environment and processing times may vary depending on connection speeds. If fast, offline analysis is required, consider using a ViewshedFunction to perform a viewshed instead.

How to use the sample

Tap the map to see all areas visible from that point within a 15km radius. Tapping on an elevated area will highlight a larger part of the surrounding landscape. It may take a few seconds for the task to run and send back the results.

How it works

1. Create a GeoprocessingTask object with the URL set to a geoprocessing service endpoint.
2. Create a FeatureCollectionTable object and add a new Feature object whose geometry is the viewshed’s observer Point.
3. Make a GeoprocessingParameters object passing in the observer point.
4. Use the geoprocessing task to create a GeoprocessingJob object with the parameters.
5. Start the job and wait for it to complete and return a GeoprocessingResult object.
6. Get the resulting GeoprocessingFeatures object.
7. Iterate through the viewshed features to use their geometry or display the geometry in a new Graphic object.

Relevant API

• FeatureCollectionTable
• GeoprocessingFeatures
• GeoprocessingJob
• GeoprocessingParameters
• GeoprocessingResult
• GeoprocessingTask

Tags

geoprocessing, heat map, heatmap, viewshed