RGB renderer

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Sample viewer app

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

screenshot

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

Tap on "Edit renderer" to change the settings for the rgb renderer. The sample allows you to change the stretch type and the parameters for each type. You can tap on the "Render" button to update the raster.

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

Relevant API

  • Basemap
  • Raster
  • RasterLayer
  • RGBRenderer
  • StretchParameters

Offline Data

Read more about how to set up the sample's offline data here.

Link Local Location
Shasta.tif raster <userhome>/ArcGIS/Runtime/Data/raster/Shasta.tif

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

RasterRgbRenderer.cppRasterRgbRenderer.cppRasterRgbRenderer.hRasterRgbRenderer.qml
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// [WriteFile Name=RasterRgbRenderer, Category=Layers]
// [Legal]
// 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.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "RasterRgbRenderer.h"

#include "Map.h"
#include "MapQuickView.h"
#include "MinMaxStretchParameters.h"
#include "PercentClipStretchParameters.h"
#include "Raster.h"
#include "RasterLayer.h"
#include "RGBRenderer.h"
#include "StandardDeviationStretchParameters.h"

#include <QDir>
#include <QtCore/qglobal.h>

#ifdef Q_OS_IOS
#include <QStandardPaths>
#endif // Q_OS_IOS

using namespace Esri::ArcGISRuntime;

// helper method to get cross platform data path
namespace
{
  QString defaultDataPath()
  {
    QString dataPath;

  #ifdef Q_OS_ANDROID
    dataPath = "/sdcard";
  #elif defined Q_OS_IOS
    dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
  #else
    dataPath = QDir::homePath();
  #endif

    return dataPath;
  }
} // namespace

RasterRgbRenderer::RasterRgbRenderer(QQuickItem* parent /* = nullptr */):
  QQuickItem(parent),
  m_dataPath(defaultDataPath() + "/ArcGIS/Runtime/Data/raster")
{
}

RasterRgbRenderer::~RasterRgbRenderer() = default;

void RasterRgbRenderer::init()
{
  // Register the map view for QML
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<RasterRgbRenderer>("Esri.Samples", 1, 0, "RasterRgbRendererSample");
}

void RasterRgbRenderer::componentComplete()
{
  QQuickItem::componentComplete();

  // find QML MapView component
  m_mapView = findChild<MapQuickView*>("mapView");
  m_mapView->setWrapAroundMode(WrapAroundMode::Disabled);

  // Create the raster and raster layer
  Raster* raster = new Raster(m_dataPath + "/Shasta.tif", this);
  m_rasterLayer = new RasterLayer(raster, this);

  // Add the raster to the map
  Basemap* basemap = new Basemap(m_rasterLayer, this);
  Map* map = new Map(basemap, this);
  m_mapView->setMap(map);
}

void RasterRgbRenderer::applyMinMax(double min0, double min1, double min2, double max0, double max1, double max2)
{
  MinMaxStretchParameters stretchParams(QList<double>{min0, min1, min2}, QList<double>{max0, max1, max2});
  RGBRenderer* renderer = new RGBRenderer(stretchParams, this);
  m_rasterLayer->setRenderer(renderer);
}

void RasterRgbRenderer::applyPercentClip(double min, double max)
{
  PercentClipStretchParameters stretchParams(min, max);
  RGBRenderer* renderer = new RGBRenderer(stretchParams, this);
  m_rasterLayer->setRenderer(renderer);
}

void RasterRgbRenderer::applyStandardDeviation(double factor)
{
  StandardDeviationStretchParameters stretchParams(factor);
  RGBRenderer* renderer = new RGBRenderer(stretchParams, this);
  m_rasterLayer->setRenderer(renderer);
}

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