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 on 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 display the geometry in a new Graphic object.
Relevant API
FeatureCollectionTable
GeoprocessingFeatures
GeoprocessingJob
GeoprocessingParameters
GeoprocessingResult
GeoprocessingTask
Tags
geoprocessing, heat map, heatmap, viewshed
Sample Code
MainActivity.java
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/* Copyright 2017 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 java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import android.graphics.Color;
import android.os.Bundle;
import android.view.MotionEvent;
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.Feature;
import com.esri.arcgisruntime.data.FeatureCollectionTable;
import com.esri.arcgisruntime.data.FeatureSet;
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.symbology.FillSymbol;
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.GeoprocessingResult;
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingTask;
publicclassMainActivityextendsAppCompatActivity{
private MapView mMapView;
private GeoprocessingTask mGeoprocessingTask;
private GeoprocessingJob mGeoprocessingJob;
private GraphicsOverlay mInputGraphicsOverlay;
private GraphicsOverlay mResultGraphicsOverlay;
// objects that implement Loadable must be class fields to prevent being garbage collected before loadingprivate FeatureCollectionTable mFeatureCollectionTable;
@OverrideprotectedvoidonCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// authentication with an API key or named user is required to access basemaps and other// location services ArcGISRuntimeEnvironment.setApiKey(BuildConfig.API_KEY);
mInputGraphicsOverlay = new GraphicsOverlay();
mResultGraphicsOverlay = new GraphicsOverlay();
// inflate MapView from layout mMapView = findViewById(R.id.mapView);
// create a map with a topographic basemap ArcGISMap map = new ArcGISMap(BasemapStyle.ARCGIS_TOPOGRAPHIC);
// set the map to be displayed in this view mMapView.setMap(map);
mMapView.setViewpoint(new Viewpoint( 45.3790902612337, 6.84905317262762, 100000));
// renderer for graphics overlays SimpleMarkerSymbol pointSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbol.Style.CIRCLE, Color.RED, 10);
SimpleRenderer renderer = new SimpleRenderer(pointSymbol);
mInputGraphicsOverlay.setRenderer(renderer);
int fillColor = Color.argb(120, 226, 119, 40);
FillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, fillColor, null);
mResultGraphicsOverlay.setRenderer(new SimpleRenderer(fillSymbol));
// add graphics overlays to the map view mMapView.getGraphicsOverlays().add(mResultGraphicsOverlay);
mMapView.getGraphicsOverlays().add(mInputGraphicsOverlay);
mGeoprocessingTask = new GeoprocessingTask(getString(R.string.viewshed_service));
mMapView.setOnTouchListener(new DefaultMapViewOnTouchListener(getApplicationContext(), mMapView) {
@OverridepublicbooleanonSingleTapConfirmed(MotionEvent e){
android.graphics.Point screenPoint = new android.graphics.Point(Math.round(e.getX()), Math.round(e.getY()));
Point mapPoint = mMapView.screenToLocation(screenPoint);
addGraphicForPoint(mapPoint);
calculateViewshedAt(mapPoint);
returnsuper.onSingleTapConfirmed(e);
}
});
}
/**
* Adds a graphic at the chosen mapPoint.
*
* @param point in MapView coordinates.
*/privatevoidaddGraphicForPoint(Point point){
// remove existing graphics mInputGraphicsOverlay.getGraphics().clear();
// new graphic Graphic graphic = new Graphic(point);
// add new graphic to the graphics overlay mInputGraphicsOverlay.getGraphics().add(graphic);
}
/**
* Uses the given point to create a FeatureCollectionTable which is passed to performGeoprocessing.
*
* @param point in MapView coordinates.
*/privatevoidcalculateViewshedAt(Point point){
// remove previous graphics mResultGraphicsOverlay.getGraphics().clear();
// cancel any previous jobif (mGeoprocessingJob != null) {
mGeoprocessingJob.cancel();
}
List<Field> fields = new ArrayList<>(1);
// create field with same alias as name Field field = Field.createString("observer", "", 8);
fields.add(field);
// create feature collection table for point geometry mFeatureCollectionTable = new FeatureCollectionTable(fields, GeometryType.POINT, point.getSpatialReference());
mFeatureCollectionTable.loadAsync();
// create a new feature and assign the geometry Feature newFeature = mFeatureCollectionTable.createFeature();
newFeature.setGeometry(point);
// add newFeature and call performGeoprocessing on done loading mFeatureCollectionTable.addFeatureAsync(newFeature);
mFeatureCollectionTable.addDoneLoadingListener(() -> {
if (mFeatureCollectionTable.getLoadStatus() == LoadStatus.LOADED) {
performGeoprocessing(mFeatureCollectionTable);
}
});
}
/**
* Creates a GeoprocessingJob from the GeoprocessingTask. Displays the resulting viewshed on the map.
*
* @param featureCollectionTable containing the observation point.
*/privatevoidperformGeoprocessing(final FeatureCollectionTable featureCollectionTable){
// geoprocessing parametersfinal ListenableFuture<GeoprocessingParameters> parameterFuture = mGeoprocessingTask.createDefaultParametersAsync();
parameterFuture.addDoneListener(() -> {
try {
GeoprocessingParameters parameters = parameterFuture.get();
parameters.setProcessSpatialReference(featureCollectionTable.getSpatialReference());
parameters.setOutputSpatialReference(featureCollectionTable.getSpatialReference());
// use the feature collection table to create the required GeoprocessingFeatures input parameters.getInputs().put("Input_Observation_Point", new GeoprocessingFeatures(featureCollectionTable));
// initialize job from mGeoprocessingTask mGeoprocessingJob = mGeoprocessingTask.createJob(parameters);
// start the job mGeoprocessingJob.start();
// listen for job success mGeoprocessingJob.addJobDoneListener(new Runnable() {
@Overridepublicvoidrun(){
if (mGeoprocessingJob.getStatus() == Job.Status.SUCCEEDED) {
GeoprocessingResult geoprocessingResult = mGeoprocessingJob.getResult();
// get the viewshed from geoprocessingResult GeoprocessingFeatures resultFeatures = (GeoprocessingFeatures) geoprocessingResult.getOutputs()
.get("Viewshed_Result");
FeatureSet featureSet = resultFeatures.getFeatures();
for (Feature feature : featureSet) {
Graphic graphic = new Graphic(feature.getGeometry());
mResultGraphicsOverlay.getGraphics().add(graphic);
}
} else {
Toast.makeText(getApplicationContext(), "Geoprocessing result failed!", Toast.LENGTH_LONG).show();
}
}
});
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
});
}
@OverrideprotectedvoidonPause(){
super.onPause();
mMapView.pause();
}
@OverrideprotectedvoidonResume(){
super.onResume();
mMapView.resume();
}
@OverrideprotectedvoidonDestroy(){
super.onDestroy();
mMapView.dispose();
}
}