Raster function service

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Load a raster from a service, then apply a function to it.

Image of apply raster function to raster from service

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.

How it works

  1. Create the ImageServiceRaster referring to the image server URL.
  2. Create the RasterFunction from a JSON string.
  3. Get the arguments of the raster function with rasterFunction.getArguments().
  4. Get the names of the raster arguments with rasterFunctionArguments.getRasterNames().
  5. Set the raster argument with rasterFunction.setRaster(rasterName, imageServiceRaster).
  6. Create a new Raster referring to the raster function.
  7. Create a RasterLayer to visualize the computed raster.
  8. 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.java
                                                                                                                   
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/* Copyright 2018 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.rasterfunctionservice;

import java.util.List;

import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.layers.RasterLayer;
import com.esri.arcgisruntime.loadable.LoadStatus;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.BasemapStyle;
import com.esri.arcgisruntime.mapping.view.MapView;
import com.esri.arcgisruntime.raster.ImageServiceRaster;
import com.esri.arcgisruntime.raster.Raster;
import com.esri.arcgisruntime.raster.RasterFunction;
import com.esri.arcgisruntime.raster.RasterFunctionArguments;

public class MainActivity extends AppCompatActivity {

  private final String TAG = MainActivity.class.getSimpleName();
  private MapView mMapView;
  private Button mRasterFunctionButton;

  @Override
  protected void onCreate(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);

    // inflate views from layout
    mMapView = findViewById(R.id.mapView);
    mRasterFunctionButton = findViewById(R.id.rasterButton);
    mRasterFunctionButton.setEnabled(false);
    // create a map with the BasemapType topographic
    ArcGISMap map = new ArcGISMap(BasemapStyle.ARCGIS_DARK_GRAY);
    final ImageServiceRaster imageServiceRaster = new ImageServiceRaster(getString(R.string.image_service_raster_url));
    final RasterLayer imageRasterLayer = new RasterLayer(imageServiceRaster);
    map.getOperationalLayers().add(imageRasterLayer);
    // zoom to the extent of the raster service
    imageRasterLayer.addDoneLoadingListener(() -> {
      if (imageRasterLayer.getLoadStatus() == LoadStatus.LOADED) {
        // get the center point
        Point centerPnt = imageServiceRaster.getServiceInfo().getFullExtent().getCenter();
        mMapView.setViewpointCenterAsync(centerPnt, 55000000);
        mRasterFunctionButton.setEnabled(true);
      } else {
        String error = "Error loading image raster layer: " + imageRasterLayer.getLoadError();
        Log.e(TAG, error);
        Toast.makeText(this, error, Toast.LENGTH_LONG).show();
      }
    });

    // update the raster with simplified hillshade
    mRasterFunctionButton.setOnClickListener(v -> applyRasterFunction(imageServiceRaster));

    // set the map to be displayed in this view
    mMapView.setMap(map);
  }

  private void applyRasterFunction(Raster raster) {
    // create raster function from json string
    RasterFunction rasterFuntionFromJson = RasterFunction.fromJson(getString(R.string.hillshade_simplified));
    // get parameter name value pairs used by hillside
    RasterFunctionArguments rasterFunctionArguments = rasterFuntionFromJson.getArguments();
    // get a list of raster names associated with the raster function
    List<String> rasterNames = rasterFunctionArguments.getRasterNames();
    rasterFunctionArguments.setRaster(rasterNames.get(0), raster);
    // create raster as raster layer
    raster = new Raster(rasterFuntionFromJson);
    RasterLayer hillshadeLayer = new RasterLayer(raster);
    mMapView.getMap().getOperationalLayers().add(hillshadeLayer);
  }

  @Override
  protected void onPause() {
    super.onPause();
    mMapView.pause();
  }

  @Override
  protected void onResume() {
    super.onResume();
    mMapView.resume();
  }

  @Override
  protected void onDestroy() {
    super.onDestroy();
    mMapView.dispose();
  }
}

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