RGB renderer

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Apply an RGB renderer to a raster layer to enhance feature visibility.

Image of RGB renderer

Use case

An RGB renderer is used to adjust the color bands of a multispectral image. Remote sensing images acquired from satellites often contain values representing the reflection of multiple spectrums of light. Changing the RGB renderer of such rasters can be used to differentiate and highlight particular features that reflect light differently, such as different vegetation types, or turbidity in water.

How to use the sample

Choose one of the stretch parameter types. The other options will adjust based on the chosen type. Add your inputs and select the 'Render' button to update the renderer.

How it works

  1. Create a Raster from a multispectral raster file.
  2. Create a RasterLayer from the raster.
  3. Create a Basemap from the raster layer and instantiate an ArcGISMap with it.
  4. Create a RGBRenderer, specifying the StretchParameters and other properties.
  5. Set the Renderer on the raster layer with rasterLayer.setRasterRenderer(renderer).

Relevant API

  • BasemapStyle
  • Raster
  • RasterLayer
  • RGBRenderer
  • StretchParameters

Offline Data

  1. Download the data from ArcGIS Online.
  2. Extract the contents of the downloaded zip file to disk.
  3. Open your command prompt and navigate to the folder where you extracted the contents of the data from step 1.
  4. Push the data into the scoped storage of the sample app: adb push raster-file /Android/data/com.esri.arcgisruntime.sample.rgbrenderer/files/raster-file

About the data

The raster used in this sample shows an area in the south of the Shasta-Trinity National Forest, California.

Tags

analysis, color, composite, imagery, multiband, multispectral, pan-sharpen, photograph, raster, spectrum, stretch, visualization

Sample Code

MainActivity.javaParametersDialogFragment.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.rgbrenderer;

import java.util.Arrays;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;
import com.esri.arcgisruntime.layers.RasterLayer;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.Basemap;
import com.esri.arcgisruntime.mapping.view.MapView;
import com.esri.arcgisruntime.raster.MinMaxStretchParameters;
import com.esri.arcgisruntime.raster.PercentClipStretchParameters;
import com.esri.arcgisruntime.raster.RGBRenderer;
import com.esri.arcgisruntime.raster.Raster;
import com.esri.arcgisruntime.raster.StandardDeviationStretchParameters;
import com.esri.arcgisruntime.raster.StretchParameters;

public class MainActivity extends AppCompatActivity implements ParametersDialogFragment.ParametersListener {

  private FragmentManager mFragmentManager;
  private MapView mMapView;
  private RasterLayer mRasterLayer;

  private int mMinR;
  private int mMaxR;
  private int mMinG;
  private int mMaxG;
  private int mMinB;
  private int mMaxB;
  private int mPercentClipMin;
  private int mPercentClipMax;
  private int mStdDevFactor;
  private StretchType mStretchType;

  @Override
  public void returnParameters(int minR, int maxR, int minG, int maxG, int minB, int maxB, int percentClipMin,
      int percentClipMax, int stdDevFactor, StretchType stretchType) {
    //gets dialog box parameters and calls updateRenderer
    mMinR = minR;
    mMaxR = maxR;
    mMinG = minG;
    mMaxG = maxG;
    mMinB = minB;
    mMaxB = maxB;
    mPercentClipMin = percentClipMin;
    mPercentClipMax = percentClipMax;
    mStdDevFactor = stdDevFactor;
    mStretchType = stretchType;
    updateRenderer();
  }

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //set default values for rgb parameters
    mMinR = 0;
    mMaxR = 255;
    mMinG = 0;
    mMaxG = 255;
    mMinB = 0;
    mMaxB = 255;
    mPercentClipMin = 0;
    mPercentClipMax = 99;
    mStdDevFactor = 1;
    mStretchType = StretchType.MIN_MAX;
    // retrieve the MapView from layout
    mMapView = findViewById(R.id.mapView);
    mFragmentManager = getSupportFragmentManager();

    // create raster
    Raster raster = new Raster(getExternalFilesDir(null) + getString(R.string.rgb_renderer_shasta_tif));
    mRasterLayer = new RasterLayer(raster);
    // create a basemap from the raster layer
    Basemap basemap = new Basemap(mRasterLayer);
    ArcGISMap map = new ArcGISMap(basemap);
    // add the map to a map view
    mMapView.setMap(map);
    updateRenderer();
  }

  /**
   * Creates StretchRenderer of the chosen type: MinMax, PercentClip or StandardDeviation.
   */
  private void updateRenderer() {
    StretchParameters stretchParameters;
    switch (mStretchType) {
      default:
        stretchParameters = new MinMaxStretchParameters(
            Arrays.asList((double) mMinR, (double) mMinG, (double) mMinB),
            Arrays.asList((double) mMaxR, (double) mMaxG, (double) mMaxB));
        break;
      case PERCENT_CLIP:
        stretchParameters = new PercentClipStretchParameters(mPercentClipMin, mPercentClipMax);
        break;
      case STANDARD_DEVIATION:
        stretchParameters = new StandardDeviationStretchParameters(mStdDevFactor);
    }
    RGBRenderer rgbRenderer = new RGBRenderer(stretchParameters, Arrays.asList(0, 1, 2), null, true);
    mRasterLayer.setRasterRenderer(rgbRenderer);
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.rgb_parameters, menu);
    return super.onCreateOptionsMenu(menu);
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    //send parameters to fragment
    ParametersDialogFragment paramDialog = new ParametersDialogFragment();
    Bundle rgbParameters = new Bundle();
    rgbParameters.putInt("minR", mMinR);
    rgbParameters.putInt("maxR", mMaxR);
    rgbParameters.putInt("minG", mMinG);
    rgbParameters.putInt("maxG", mMaxG);
    rgbParameters.putInt("minB", mMinB);
    rgbParameters.putInt("maxB", mMaxB);
    rgbParameters.putInt("percent_clip_min", mPercentClipMin);
    rgbParameters.putInt("percent_clip_max", mPercentClipMax);
    rgbParameters.putInt("std_dev_factor", mStdDevFactor);
    rgbParameters.putSerializable("stretch_type", mStretchType);
    paramDialog.setArguments(rgbParameters);
    paramDialog.show(mFragmentManager, "param_dialog");
    return super.onOptionsItemSelected(item);
  }

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

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

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

  enum StretchType {
    MIN_MAX("Min Max"),
    PERCENT_CLIP("Percent Clip"),
    STANDARD_DEVIATION("Standard Deviation");

    private final String stringValue;

    StretchType(String toString) {
      stringValue = toString;
    }

    @Override public String toString() {
      return stringValue;
    }
  }
}

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