Load a raster from a service, then apply a function to it.
Use case
Raster functions allow processing operations that can be applied to one or more rasters on the fly. Functions can be applied to rasters that come from a service. A land survey agency may apply hillshade and aspect functions to rasters with elevation data in order to better determine the topography of a landscape and to make further planning decisions.
How to use the sample
Tap the "Apply Layer" button to apply the raster function and display the result. Tap "Reset" to apply the image service raster back to the rasterLayer.
How it works
Create the ImageServiceRaster referring to the image server URL.
Create the RasterFunction from a JSON string.
Get the arguments of the raster function with rasterFunction.arguments.
Get the names of the raster arguments with rasterFunctionArguments.rasterNames.
Set the raster argument with rasterFunctionArguments.setRaster(rasterNames[0], imageServiceRaster).
Create a new Raster referring to the raster function.
Create a RasterLayer to visualize the computed raster.
Display the raster.
Relevant API
ImageServiceRaster
Raster
RasterFunction
RasterFunctionArguments
RasterLayer
About the data
The sample applies a hillshade function to a raster produced from the National Land Cover Database, NLCDLandCover2001. You can learn more about the hillshade function in the ArcMap documentation.
Additional information
The raster function computation happens locally on the client device.
Tags
function, layer, raster, raster function, service
Sample Code
MainActivity.kt
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/* Copyright 2023 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.applyfunctiontorasterfromservice
import android.os.Bundle
import android.util.Log
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.lifecycleScope
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.arcgismaps.LoadStatus
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.layers.RasterLayer
import com.arcgismaps.raster.ImageServiceRaster
import com.arcgismaps.raster.Raster
import com.arcgismaps.raster.RasterFunction
import com.esri.arcgismaps.sample.applyfunctiontorasterfromservice.databinding.ActivityMainBinding
import com.google.android.material.snackbar.Snackbar
import kotlinx.coroutines.launch
classMainActivity : AppCompatActivity() {
privateval activityMainBinding: ActivityMainBinding by lazy {
DataBindingUtil.setContentView(this, R.layout.activity_main)
}
privateval mapView by lazy {
activityMainBinding.mapView
}
privateval imageServiceRaster: ImageServiceRaster by lazy {
ImageServiceRaster(getString(R.string.image_service_raster_url))
}
privateval imageRasterLayer: RasterLayer by lazy {
RasterLayer(imageServiceRaster)
}
overridefunonCreate(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.API_KEY)
lifecycle.addObserver(mapView)
// create and add a map with a dark gray basemap styleval map = ArcGISMap(BasemapStyle.ArcGISDarkGray)
mapView.map = map
// add the imageRasterLayer to the map addImageRasterLayer()
activityMainBinding.apply {
rasterButton.setOnClickListener {
// update the raster with simplified hillshade applyRasterFunction()
resetButton.isEnabled = true rasterButton.isEnabled = false }
resetButton.setOnClickListener {
// reset map to back to the RasterLayer addImageRasterLayer()
resetButton.isEnabled = false rasterButton.isEnabled = true }
}
}
/**
* Adds the image raster layer to the map and set's the viewpoint
* to the image server raster's bounding geometry
*/privatefunaddImageRasterLayer() {
// clear and add the imageRasterLayer to the map mapView.map?.operationalLayers?.apply {
clear()
add(imageRasterLayer)
}
// collect the load status of the RasterLayer lifecycleScope.launch {
imageRasterLayer.loadStatus.collect { loadStatus ->
if (loadStatus == LoadStatus.Loaded) {
// get the center point of the image service rasterval extentEnvelope = imageServiceRaster.serviceInfo?.fullExtent
?: return@collect showError("Error retrieving the ArcGISImageServiceInfo")
// set the viewpoint of the map to the envelope mapView.setViewpointGeometry(extentEnvelope)
} elseif (loadStatus is LoadStatus.FailedToLoad) {
showError("Error loading image raster layer: ${loadStatus.error.message}")
}
}
}
}
/**
* Create a hillshade layer using a custom JSON raster function.
*/privatefunapplyRasterFunction() {
// create raster function from json stringval rasterFunction = RasterFunction.fromJsonOrNull(getString(R.string.hillshade_simplified))
?: return showError("Error creating a raster function object from JSON")
// get parameter name value pairs used by hillsideval rasterFunctionArguments = rasterFunction.arguments
?: return showError("Raster function arguments is null")
// get a list of raster names associated with the raster functionval rasterNames = rasterFunctionArguments.rasterNames
// check if raster function arguments contains raster variable namesif(rasterNames.isNotEmpty()){
// using the first raster variable name rasterFunctionArguments.setRaster(rasterNames[0], imageServiceRaster)
// create raster as raster layerval hillshadeRaster = Raster.createWithRasterFunction(rasterFunction)
val hillshadeLayer = RasterLayer(hillshadeRaster)
// clear and add the layer to the map mapView.map?.operationalLayers?.add(hillshadeLayer)
} else{
showError("Raster function arguments does not contain raster variable names")
}
}
privatefunshowError(message: String) {
Log.e(localClassName, message)
Snackbar.make(mapView, message, Snackbar.LENGTH_SHORT).show()
}
}