Blend raster layer

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Blend a hillshade with a raster by specifying the elevation data. The resulting raster looks similar to the original raster, but with some terrain shading, giving it a textured look.

screenshot

Use case

BlendRenderer can be used to apply a color ramp to a hillshade to emphasize areas of high or low elevation. A BlendRenderer can also be used to add a hillshade effect to aerial or satellite imagery, thereby making changes in elevation more visible.

How to use the sample

Tap on "Edit Renderer" in the toolbar to change the settings for the blend renderer. Choose and adjust the altitude, azimuth, slope type and color ramp type settings to update the image.

How it works

  1. Create a Raster object from a raster file.
  2. Create a RasterLayer object from the raster.
  3. Create a Basemap object from the raster layer and set it to the map.
  4. Create another Raster object for elevation from a grayscale raster file.
  5. Create a BlendRenderer object, specifying the elevation raster, color ramp, and other properties.
    • If you specify a non-null color ramp, use the elevation raster as the base raster in addition to the elevation raster parameter. That way, the color ramp is used instead of the satellite imagery.
  6. Set the blend renderer to the raster layer.

Relevant API

  • BlendRenderer
  • ColorRamp
  • Raster
  • RasterLayer

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
Shasta_Elevation.tif raster <userhome>/ArcGIS/Runtime/Data/raster/Shasta_Elevation.tif

Tags

color ramp, elevation, hillshade, image, raster, raster layer, visualization

Sample Code

BlendRasterLayer.cppBlendRasterLayer.cppBlendRasterLayer.hColorRampModel.qmlSlopeTypeModel.qmlBlendRasterLayer.qml
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// [WriteFile Name=BlendRasterLayer, 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 "BlendRasterLayer.h"

#include "Map.h"
#include "MapQuickView.h"
#include "Raster.h"
#include "RasterLayer.h"
#include "BlendRenderer.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

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

BlendRasterLayer::~BlendRasterLayer() = default;

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

void BlendRasterLayer::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);

  m_elevationRaster = new Raster(m_dataPath + "/Shasta_Elevation.tif", this);
  m_rasterLayerColorRamp = new RasterLayer(m_elevationRaster, this);

  // Add the raster to the map
  m_basemap = new Basemap(m_rasterLayer, this);
  m_basemapColorRamp = new Basemap(m_rasterLayerColorRamp, this);
  m_map = new Map(m_basemap, this);
  m_mapView->setMap(m_map);
}

void BlendRasterLayer::applyRenderSettings(double altitude, double azimuth, int slopeTypeVal, int colorRampTypeVal)
{
  PresetColorRampType colorRampType = static_cast<PresetColorRampType>(colorRampTypeVal);
  RasterLayer* rasterLyr = rasterLayer(colorRampType != PresetColorRampType::None);
  if (!rasterLyr)
    return;

  QList<double> outputMinValues{9};
  QList<double> outputMaxValues{255};
  QList<double> sourceMinValues;
  QList<double> sourceMaxValues;
  QList<double> noDataValues;
  QList<double> gammas;
  double zFactor = 1.;
  double pixelSizeFactor = 1.;
  double pixelSizePower = 1.;
  int outputBitDepth = 8;
  ColorRamp* colorRamp = ColorRamp::create(colorRampType, 800, this);
  SlopeType slopeType = static_cast<SlopeType>(slopeTypeVal);

  BlendRenderer* renderer = new BlendRenderer(m_elevationRaster,
                                              outputMinValues,
                                              outputMaxValues,
                                              sourceMinValues,
                                              sourceMaxValues,
                                              noDataValues,
                                              gammas,
                                              colorRamp,
                                              altitude,
                                              azimuth,
                                              zFactor,
                                              slopeType,
                                              pixelSizeFactor,
                                              pixelSizePower,
                                              outputBitDepth,
                                              this);

  rasterLyr->setRenderer(renderer);
}

RasterLayer* BlendRasterLayer::rasterLayer(bool useColorRamp)
{
  m_map->setBasemap(useColorRamp ? m_basemapColorRamp : m_basemap);
  return useColorRamp ? m_rasterLayerColorRamp : m_rasterLayer;
}

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