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.
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
Create a GeoprocessingTask object with the URL set to a geoprocessing service endpoint.
Create a FeatureCollectionTable object and add a new Feature object whose geometry is the viewshed's observer Point.
Make a GeoprocessingParameters object passing in the observer point.
Use the geoprocessing task to create a GeoprocessingJob object with the parameters.
Start the job and wait for it to complete and return a GeoprocessingResult object.
Get the resulting GeoprocessingFeatures object.
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
analysis, geoprocessing, heat map, viewshed
Sample Code
MainActivity.kt
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/* Copyright 2020 Esri
*
* Licensed under the Apache License, Version 2.0 (the "License")
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/package com.esri.arcgisruntime.sample.viewshedgeoprocessing
import android.graphics.Color
import android.os.Bundle
import android.util.Log
import android.view.MotionEvent
import android.view.View
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment
import com.esri.arcgisruntime.concurrent.Job
import com.esri.arcgisruntime.concurrent.ListenableFuture
import com.esri.arcgisruntime.data.FeatureCollectionTable
import com.esri.arcgisruntime.data.Field
import com.esri.arcgisruntime.geometry.GeometryType
import com.esri.arcgisruntime.geometry.Point
import com.esri.arcgisruntime.loadable.LoadStatus
import com.esri.arcgisruntime.mapping.ArcGISMap
import com.esri.arcgisruntime.mapping.BasemapStyle
import com.esri.arcgisruntime.mapping.Viewpoint
import com.esri.arcgisruntime.mapping.view.DefaultMapViewOnTouchListener
import com.esri.arcgisruntime.mapping.view.Graphic
import com.esri.arcgisruntime.mapping.view.GraphicsOverlay
import com.esri.arcgisruntime.mapping.view.MapView
import com.esri.arcgisruntime.sample.viewshedgeoprocessing.databinding.ActivityMainBinding
import com.esri.arcgisruntime.symbology.SimpleFillSymbol
import com.esri.arcgisruntime.symbology.SimpleMarkerSymbol
import com.esri.arcgisruntime.symbology.SimpleRenderer
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingFeatures
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingJob
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingParameters
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingTask
import java.util.concurrent.ExecutionException
import kotlin.math.roundToInt
classMainActivity : AppCompatActivity() {
privateval TAG: String = this::class.java.simpleName
privateval activityMainBinding by lazy {
ActivityMainBinding.inflate(layoutInflater)
}
privateval mapView: MapView by lazy {
activityMainBinding.mapView
}
privateval loadingView: View by lazy {
activityMainBinding.loadingView
}
privateval geoprocessingTask: GeoprocessingTask by lazy { GeoprocessingTask(getString(R.string.viewshed_service)) }
privatevar geoprocessingJob: GeoprocessingJob? = nullprivateval inputGraphicsOverlay: GraphicsOverlay by lazy { GraphicsOverlay() }
privateval resultGraphicsOverlay: GraphicsOverlay by lazy { GraphicsOverlay() }
// objects that implement Loadable must be class fields to prevent being garbage collected before loadingprivatelateinitvar featureCollectionTable: FeatureCollectionTable
overridefunonCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(activityMainBinding.root)
// authentication with an API key or named user is required to access basemaps and other// location services ArcGISRuntimeEnvironment.setApiKey(BuildConfig.API_KEY)
// create renderers for graphics overlaysval fillColor = Color.argb(120, 226, 119, 40)
val fillSymbol = SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, fillColor, null)
resultGraphicsOverlay.renderer = SimpleRenderer(fillSymbol)
val pointSymbol = SimpleMarkerSymbol(
SimpleMarkerSymbol.Style.CIRCLE,
Color.RED,
10F )
inputGraphicsOverlay.renderer = SimpleRenderer(pointSymbol)
mapView.apply {
// create a map with the Basemap type topographic map = ArcGISMap(BasemapStyle.ARCGIS_TOPOGRAPHIC)
// set the viewpoint setViewpoint(Viewpoint(45.3790, 6.8490, 100000.0))
// add graphics overlays to the map view graphicsOverlays.addAll(listOf(resultGraphicsOverlay, inputGraphicsOverlay))
// add onTouchListener for calculating the new viewshed onTouchListener = object : DefaultMapViewOnTouchListener(
applicationContext,
mapView
) {
overridefunonSingleTapConfirmed(e: MotionEvent): Boolean {
val screenPoint = android.graphics.Point(
e.x.roundToInt(),
e.y.roundToInt()
)
val mapPoint = mMapView.screenToLocation(screenPoint)
addGraphicForPoint(mapPoint)
calculateViewshedFrom(mapPoint)
returnsuper.onSingleTapConfirmed(e)
}
}
}
}
/**
* Adds a graphic at the chosen mapPoint.
*
* @param point in MapView coordinates.
*/privatefunaddGraphicForPoint(point: Point) {
// remove existing graphics inputGraphicsOverlay.graphics.clear()
// add new graphic to the graphics overlay inputGraphicsOverlay.graphics.add(Graphic(point))
}
/**
* Uses the given point to create a FeatureCollectionTable which is passed to performGeoprocessing.
*
* @param point in MapView coordinates.
*/privatefuncalculateViewshedFrom(point: Point) {
// display the LoadingView while calculating the Viewshed loadingView.visibility = View.VISIBLE
// remove previous graphics resultGraphicsOverlay.graphics.clear()
// cancel any previous job geoprocessingJob?.cancelAsync()
// create field with same alias as nameval field = Field.createString("observer", "", 8)
// create feature collection table for point geometry featureCollectionTable =
FeatureCollectionTable(listOf(field), GeometryType.POINT, point.spatialReference)
featureCollectionTable.loadAsync()
// create a new feature and assign the geometryval newFeature = featureCollectionTable.createFeature().apply {
geometry = point
}
// add newFeature and call perform Geoprocessing on done loading featureCollectionTable.addFeatureAsync(newFeature)
featureCollectionTable.addDoneLoadingListener {
if (featureCollectionTable.loadStatus == LoadStatus.LOADED) {
performGeoprocessing(featureCollectionTable)
}
}
}
/**
* Creates a GeoprocessingJob from the GeoprocessingTask. Displays the resulting viewshed on the map.
*
* @param featureCollectionTable the feature collection table containing the observation point.
*/privatefunperformGeoprocessing(featureCollectionTable: FeatureCollectionTable) {
// geoprocessing parametersval parameterFuture: ListenableFuture<GeoprocessingParameters> =
geoprocessingTask.createDefaultParametersAsync()
parameterFuture.addDoneListener {
try {
val parameters = parameterFuture.get().apply {
processSpatialReference = featureCollectionTable.spatialReference
outputSpatialReference = featureCollectionTable.spatialReference
// use the feature collection table to create the required GeoprocessingFeatures input inputs["Input_Observation_Point"] =
GeoprocessingFeatures(featureCollectionTable)
}
// initialize job from geoprocessingTask geoprocessingJob = geoprocessingTask.createJob(parameters)
// start the job geoprocessingJob?.start()
// listen for job success geoprocessingJob?.addJobDoneListener {
// hide the LoadingView when job is done loading loadingView.visibility = View.GONE
if (geoprocessingJob?.status == Job.Status.SUCCEEDED) {
// get the viewshed from geoprocessingResult (geoprocessingJob?.result?.outputs?.get("Viewshed_Result") as? GeoprocessingFeatures)?.let { viewshedResult ->
// for each feature in the resultfor (feature in viewshedResult.features) {
// add the feature as a graphic resultGraphicsOverlay.graphics.add(Graphic(feature.geometry))
}
}
} else {
Toast.makeText(
applicationContext,
"Geoprocessing result failed!",
Toast.LENGTH_LONG
).show()
Log.e(TAG, geoprocessingJob?.error?.cause.toString())
}
}
} catch (e: Exception) {
when (e) {
is InterruptedException, is ExecutionException -> ("Error getting geoprocessing result: " + e.message).also {
Toast.makeText(this, it, Toast.LENGTH_LONG).show()
Log.e(TAG, it)
}
else -> throw e
}
}
}
}
overridefunonResume() {
super.onResume()
mapView.resume()
}
overridefunonPause() {
mapView.pause()
super.onPause()
}
overridefunonDestroy() {
mapView.dispose()
super.onDestroy()
}
}