Show viewshed calculated from geoprocessing task | ArcGIS Maps SDK for Kotlin

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Sample viewer app

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

Image of show viewshed calculated from geoprocessing task

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

Click the map to see all areas visible from that point within a 15km radius. Clicking on an elevated and unobstructed 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 and pass in the GeoprocessingFeatures table which contains the observation point as an input parameter.
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 GeoprocessingFeatures to use their geometry or display the geometry in a new Graphic object.

Relevant API

FeatureCollectionTable
GeoprocessingFeatures
GeoprocessingJob
GeoprocessingParameters
GeoprocessingResult
GeoprocessingTask

Sample Code

MainActivity.kt

MapViewModel.kt

MainScreen.kt

/* Copyright 2025 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.arcgismaps.sample.showviewshedcalculatedfromgeoprocessingtask

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.runtime.Composable
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.esri.arcgismaps.sample.sampleslib.theme.SampleAppTheme
import com.esri.arcgismaps.sample.showviewshedcalculatedfromgeoprocessingtask.screens.MainScreen

class MainActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // authentication with an API key or named user is
        // required to access basemaps and other location services
        ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.ACCESS_TOKEN)

        enableEdgeToEdge()
        setContent {
            SampleAppTheme {
                ShowViewshedCalculatedFromGeoprocessingTaskApp()
            }
        }
    }

    @Composable
    private fun ShowViewshedCalculatedFromGeoprocessingTaskApp() {
        Surface(color = MaterialTheme.colorScheme.background) {
            MainScreen(
                sampleName = getString(R.string.show_viewshed_calculated_from_geoprocessing_task_app_name)
            )
        }
    }
}

/* Copyright 2025 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.arcgismaps.sample.showviewshedcalculatedfromgeoprocessingtask.components

import android.app.Application
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.viewModelScope
import com.arcgismaps.Color
import com.arcgismaps.data.FeatureCollectionTable
import com.arcgismaps.geometry.GeodeticCurveType
import com.arcgismaps.geometry.GeometryEngine
import com.arcgismaps.geometry.GeometryType
import com.arcgismaps.geometry.LinearUnit
import com.arcgismaps.geometry.Point
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.symbology.SimpleFillSymbol
import com.arcgismaps.mapping.symbology.SimpleFillSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleMarkerSymbol
import com.arcgismaps.mapping.symbology.SimpleMarkerSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleRenderer
import com.arcgismaps.mapping.view.Graphic
import com.arcgismaps.mapping.view.GraphicsOverlay
import com.arcgismaps.mapping.view.SingleTapConfirmedEvent
import com.arcgismaps.tasks.geoprocessing.GeoprocessingExecutionType
import com.arcgismaps.tasks.geoprocessing.GeoprocessingJob
import com.arcgismaps.tasks.geoprocessing.GeoprocessingParameters
import com.arcgismaps.tasks.geoprocessing.GeoprocessingTask
import com.arcgismaps.tasks.geoprocessing.geoprocessingparameters.GeoprocessingFeatures
import com.arcgismaps.tasks.geoprocessing.geoprocessingparameters.GeoprocessingLinearUnit
import com.arcgismaps.toolkit.geoviewcompose.MapViewProxy
import com.esri.arcgismaps.sample.sampleslib.components.MessageDialogViewModel
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.launch

class MapViewModel(application: Application) :
    AndroidViewModel(application) {

    // ArcGISMap with a topographic basemap
    val arcGISMap: ArcGISMap = ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
        initialViewpoint = Viewpoint(
            latitude = 45.379,
            longitude = 6.849,
            scale = 144447.0
        )
    }

    // Used by the composable MapView for viewpoint changes
    val mapviewProxy = MapViewProxy()

    // Graphics overlay for the red marker at the tapped location
    val inputGraphicsOverlay = GraphicsOverlay().apply {
        renderer = SimpleRenderer(
            symbol = SimpleMarkerSymbol(
                style = SimpleMarkerSymbolStyle.Circle,
                color = Color.red,
                size = 10f
            )
        )
    }

    // Graphics overlay for displaying the resulting viewshed polygons
    val resultGraphicsOverlay = GraphicsOverlay().apply {
        renderer = SimpleRenderer(
            symbol = SimpleFillSymbol(
                style = SimpleFillSymbolStyle.Solid,
                color = Color.fromRgba(r = 255, g = 165, b = 0, a = 100)
            )
        )
    }

    // Graphics overlay for displaying the 15 km buffer range
    val bufferGraphicsOverlay = GraphicsOverlay().apply {
        renderer = SimpleRenderer(
            symbol = SimpleFillSymbol(
                style = SimpleFillSymbolStyle.Solid,
                color = Color.fromRgba(r = 0, g = 0, b = 255, a = 50)
            )
        )
    }

    // GeoprocessingTask pointing to the Viewshed service URL
    private val geoprocessingTask = GeoprocessingTask(
        url = "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Elevation/ESRI_Elevation_World/GPServer/Viewshed"
    )

    // Running GeoprocessingJob for cancellation/cleanup
    private var geoprocessingJob: GeoprocessingJob? = null

    // State flows for controlling UI
    private val _isGeoprocessingInProgress = MutableStateFlow(false)
    val isGeoprocessingInProgress = _isGeoprocessingInProgress.asStateFlow()

    // Message dialog view model for handling error messages
    val messageDialogVM = MessageDialogViewModel()

    init {
        viewModelScope.launch {
            arcGISMap.load().onFailure { messageDialogVM.showMessageDialog(it) }
        }
    }

    /**
     * Handles the [singleTapConfirmedEvent] by retrieving the tapped [Point] to
     * cancel and run a new viewshed geoprocessing job.
     */
    fun onMapTapped(singleTapConfirmedEvent: SingleTapConfirmedEvent) {
        val tapPoint = singleTapConfirmedEvent.mapPoint
            ?: return messageDialogVM.showMessageDialog("Unable to retrieve tapped point")
        viewModelScope.launch {
            // Clear existing overlays and cancel any running job
            clearOverlays()
            geoprocessingJob?.cancel()
            // Add a new red marker to the map at the tapped point
            addTapMarker(tapPoint)
            // Show a 15 km buffer to visualize the visibility range
            addBufferGraphic(tapPoint)
            // Start the geoprocessing job to obtain the viewshed polygons
            _isGeoprocessingInProgress.value = true
            calculateViewshed(tapPoint)
            _isGeoprocessingInProgress.value = false
        }
    }

    /**
     * Perform the viewshed calculation on the geoprocessing service
     * for the given [tapPoint].
     */
    private suspend fun calculateViewshed(tapPoint: Point) {
        // Create an empty FeatureCollectionTable for the tapped location
        val table = FeatureCollectionTable(
            fields = emptyList(),
            geometryType = GeometryType.Point,
            spatialReference = tapPoint.spatialReference
        )

        // Create a new feature with the tapped geometry and add to the table
        val newFeature = table.createFeature().also { it.geometry = tapPoint }
        table.addFeature(newFeature)

        // Create geoprocessing parameters for a synchronous execution
        val geoprocessingParameters = GeoprocessingParameters(
            geoprocessingExecutionType = GeoprocessingExecutionType.SynchronousExecute
        ).apply {
            processSpatialReference = tapPoint.spatialReference
            outputSpatialReference = tapPoint.spatialReference
            // Provide the tapped point as "Input_Observation_Point"
            inputs["Input_Observation_Point"] = GeoprocessingFeatures(featureSet = table)
            inputs["Viewshed_Distance"] = GeoprocessingLinearUnit(distance = 15000.0)
        }

        // Create a new job
        geoprocessingJob = geoprocessingTask.createJob(geoprocessingParameters)

        // Start and await the result
        geoprocessingJob?.start()

        val gpResult = geoprocessingJob?.result()?.getOrElse {
            return messageDialogVM.showMessageDialog(it)
        }

        // Get the output features for the viewshed polygon
        val viewshedFeatureSet = gpResult?.outputs?.get("Viewshed_Result") as? GeoprocessingFeatures
            ?: return messageDialogVM.showMessageDialog("No viewshed result found in the geoprocessing job.")
        val featureSet = viewshedFeatureSet.features
            ?: return messageDialogVM.showMessageDialog("Geoprocessing feature set is null.")

        // Add each resulting feature geometry as a graphic to resultGraphicsOverlay
        val resultGraphics = featureSet.mapNotNull { feature ->
            feature.geometry?.let { Graphic(it) }
        }

        // Add the graphics to the overlay and set the map's viewpoint to its extent
        resultGraphicsOverlay.graphics.addAll(resultGraphics)
        resultGraphicsOverlay.extent?.let { resultExtent ->
            mapviewProxy.setViewpointGeometry(
                boundingGeometry = resultExtent,
                paddingInDips = 20.0
            )
        }
    }

    /**
     * Place a simple red marker graphic at the tapped location.
     */
    private fun addTapMarker(tapPoint: Point) {
        val graphic = Graphic(tapPoint)
        inputGraphicsOverlay.graphics.add(graphic)
    }

    /**
     * Add a 15 km buffer graphic around [tapPoint].
     */
    private fun addBufferGraphic(tapPoint: Point, radiusMeters: Double = 15000.0) {
        // Use the geometry engine to build a geodesic planar buffer
        val bufferGeometry = GeometryEngine.bufferGeodeticOrNull(
            geometry = tapPoint,
            distance = radiusMeters,
            distanceUnit = LinearUnit.meters,
            maxDeviation = Double.NaN,
            curveType = GeodeticCurveType.Geodesic
        )
        // Create a graphic from the buffered geometry
        val bufferGraphic = Graphic(bufferGeometry)
        // Add it to the buffer graphics overlay
        bufferGraphicsOverlay.graphics.add(bufferGraphic)
    }

    /**
     * Clear any previous marker or result polygons from the map.
     */
    private fun clearOverlays() {
        inputGraphicsOverlay.graphics.clear()
        resultGraphicsOverlay.graphics.clear()
        bufferGraphicsOverlay.graphics.clear()
    }
}

/* Copyright 2025 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.arcgismaps.sample.showviewshedcalculatedfromgeoprocessingtask.screens

import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.Scaffold
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
import androidx.compose.ui.Modifier
import androidx.lifecycle.viewmodel.compose.viewModel
import com.arcgismaps.toolkit.geoviewcompose.MapView
import com.esri.arcgismaps.sample.sampleslib.components.LoadingDialog
import com.esri.arcgismaps.sample.sampleslib.components.MessageDialog
import com.esri.arcgismaps.sample.sampleslib.components.SampleTopAppBar
import com.esri.arcgismaps.sample.showviewshedcalculatedfromgeoprocessingtask.components.MapViewModel

/**
 * Main screen layout for the sample app
 */
@Composable
fun MainScreen(sampleName: String) {
    val mapViewModel: MapViewModel = viewModel()

    // Observe geoprocessing state from the view model
    val isGeoprocessingInProgress by mapViewModel.isGeoprocessingInProgress.collectAsState()

    Scaffold(
        topBar = { SampleTopAppBar(title = sampleName) },
        content = {
            Column(
                modifier = Modifier
                    .fillMaxSize()
                    .padding(it),
            ) {
                MapView(
                    modifier = Modifier
                        .fillMaxSize()
                        .weight(1f),
                    arcGISMap = mapViewModel.arcGISMap,
                    onSingleTapConfirmed = mapViewModel::onMapTapped,
                    mapViewProxy = mapViewModel.mapviewProxy,
                    graphicsOverlays = listOf(
                        mapViewModel.inputGraphicsOverlay,
                        mapViewModel.bufferGraphicsOverlay,
                        mapViewModel.resultGraphicsOverlay
                    )
                )
            }

            mapViewModel.messageDialogVM.apply {
                if (dialogStatus) {
                    MessageDialog(
                        title = messageTitle,
                        description = messageDescription,
                        onDismissRequest = ::dismissDialog
                    )
                }
            }

            // If geoprocessing is running, show a loading dialog
            if (isGeoprocessingInProgress) {
                LoadingDialog(loadingMessage = "Calculating viewshed…")
            }
        }
    )
}

Use case

How to use the sample

How it works

Relevant API

Tags

Sample Code