Apply a colormap renderer to a raster.

Use case
A colormap renderer transforms pixel values in a raster to display raster data based on specific colors, aiding in visual analysis of the data. For example, a forestry commission may want to quickly visualize areas above and below the tree-line line occurring at a know elevation on a raster containing elevation values. They could overlay a transparent colormap set to color those areas below the tree-line elevation green, and those above white.
How to use the sample
Pan and zoom to explore the effect of the colormap applied to the raster.
How it works
- Create a
Rasterfrom a raster file. - Create a
RasterLayerfrom the raster. - Create a
QList<QColor>: colors at the beginning of the list replace the darkest values in the raster and colors at the end of the list replaced the brightest values of the raster. - Create a colormap renderer with the color list and apply it to the raster layer with
RasterLayer::setRenderer(RasterRenderer *renderer).
Relevant API
- ColormapRenderer
- Raster
- RasterLayer
Offline Data
Read more about how to set up the sample’s offline data here.
| Link | Local Location |
|---|---|
| ShastaBW.tif raster | <userhome>/ArcGIS/Runtime/Data/raster/ShastaBW.tif |
About the data
The raster used in this sample shows an area in the south of the Shasta-Trinity National Forest, California.
Tags
colormap, data, raster, renderer, visualization
Sample Code
// [WriteFile Name=RasterColormapRenderer, 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
// sample headers#include "RasterColormapRenderer.h"
// ArcGIS Maps SDK headers#include "ColormapRenderer.h"#include "Envelope.h"#include "Error.h"#include "LayerListModel.h"#include "Map.h"#include "MapQuickView.h"#include "MapTypes.h"#include "MapViewTypes.h"#include "Raster.h"#include "RasterLayer.h"
// Qt headers#include <QFuture>#include <QStandardPaths>#include <QtCore/qglobal.h>
using namespace Esri::ArcGISRuntime;
// helper method to get cross platform data pathnamespace{QString defaultDataPath(){ QString dataPath;
#ifdef Q_OS_IOS dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);#else dataPath = QStandardPaths::writableLocation(QStandardPaths::HomeLocation);#endif
return dataPath;}} // namespace
RasterColormapRenderer::RasterColormapRenderer(QQuickItem* parent /* = nullptr */): QQuickItem(parent), m_dataPath(defaultDataPath() + "/ArcGIS/Runtime/Data/raster"){}
RasterColormapRenderer::~RasterColormapRenderer() = default;void RasterColormapRenderer::init(){ // Register the map view for QML qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView"); qmlRegisterType<RasterColormapRenderer>("Esri.Samples", 1, 0, "RasterColormapRendererSample");}
void RasterColormapRenderer::componentComplete(){ QQuickItem::componentComplete();
// find QML MapView component m_mapView = findChild<MapQuickView*>("mapView"); m_mapView->setWrapAroundMode(WrapAroundMode::Disabled);
//! [RasterColormapRenderer cpp add raster basemap] // Create the raster and raster layer Raster* raster = new Raster(m_dataPath + "/ShastaBW.tif", this); m_rasterLayer = new RasterLayer(raster, this);
connect(m_rasterLayer, &RasterLayer::doneLoading, this, [this](const Error& error) { if (!error.isEmpty()) { qDebug() << error.message() << error.additionalMessage(); return; }
m_mapView->setViewpointGeometryAsync(m_rasterLayer->fullExtent(), 50); });
ColormapRenderer* colormapRenderer = createRenderer();
// set the colormap renderer on the raster layer m_rasterLayer->setRenderer(colormapRenderer);
// Add the raster to the map as an operational layer Map* map = new Map(BasemapStyle::ArcGISImageryStandard, this);
map->operationalLayers()->append(m_rasterLayer);
m_mapView->setMap(map); //! [RasterColormapRenderer cpp add raster basemap]}
ColormapRenderer *RasterColormapRenderer::createRenderer(){ // create a color map where values 0-150 are red and 150-250 are yellow QList<QColor> colors; colors.reserve(250); for (int i = 0; i < 250; ++i) colors.append( i < 150 ? Qt::red : Qt::yellow);
// create a colormap renderer ColormapRenderer* colormapRenderer = new ColormapRenderer(colors, this);
return colormapRenderer;}// [WriteFile Name=RasterColormapRenderer, 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]
#ifndef COLORMAPRENDERER_H#define COLORMAPRENDERER_H
// Qt headers#include <QQuickItem>
namespace Esri::ArcGISRuntime{ class ColormapRenderer; class Map; class MapQuickView; class RasterLayer;}
class RasterColormapRenderer : public QQuickItem{ Q_OBJECT
public: explicit RasterColormapRenderer(QQuickItem* parent = nullptr); ~RasterColormapRenderer() override;
static void init();
void componentComplete() override;
private: Esri::ArcGISRuntime::ColormapRenderer* createRenderer();
Esri::ArcGISRuntime::Map* m_map = nullptr; Esri::ArcGISRuntime::MapQuickView* m_mapView = nullptr; Esri::ArcGISRuntime::RasterLayer* m_rasterLayer = nullptr; QString m_dataPath;};
#endif // COLORMAPRENDERER_H// [WriteFile Name=RasterColormapRenderer, 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]
import QtQuickimport QtQuick.Controlsimport Esri.Samples
RasterColormapRendererSample { id: rootRectangle clip: true width: 800 height: 800
// add a mapView component MapView { anchors.fill: parent objectName: "mapView"
Component.onCompleted: { // Set the focus on MapView to initially enable keyboard navigation forceActiveFocus(); } }}// [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]
// sample headers#include "RasterColormapRenderer.h"
// ArcGIS Maps SDK headers#include "ArcGISRuntimeEnvironment.h"
// Qt headers#include <QCommandLineParser>#include <QDir>#include <QGuiApplication>#include <QQmlEngine>#include <QQuickView>
// Platform specific headers#ifdef Q_OS_WIN#include <Windows.h>#endif
#define STRINGIZE(x) #x#define QUOTE(x) STRINGIZE(x)
int main(int argc, char *argv[]){ Esri::ArcGISRuntime::ArcGISRuntimeEnvironment::setUseLegacyAuthentication(false); QGuiApplication app(argc, argv); app.setApplicationName(QString("RasterColormapRenderer"));
// Use of ArcGIS location services, such as basemap styles, geocoding, and routing services, // requires an access token. For more information see // https://links.esri.com/arcgis-runtime-security-auth.
// The following methods grant an access token:
// 1. User authentication: Grants a temporary access token associated with a user's ArcGIS account. // To generate a token, a user logs in to the app with an ArcGIS account that is part of an // organization in ArcGIS Online or ArcGIS Enterprise.
// 2. API key authentication: Get a long-lived access token that gives your application access to // ArcGIS location services. Go to the tutorial at https://links.esri.com/create-an-api-key. // Copy the API Key access token.
const QString accessToken = QString("");
if (accessToken.isEmpty()) { qWarning() << "Use of ArcGIS location services, such as the basemap styles service, requires" << "you to authenticate with an ArcGIS account or set the API Key property."; } else { Esri::ArcGISRuntime::ArcGISRuntimeEnvironment::setApiKey(accessToken); }
//Initialize the sample RasterColormapRenderer::init();
// Initialize application view QQuickView view; view.setResizeMode(QQuickView::SizeRootObjectToView);
// Add the import Path view.engine()->addImportPath(QDir(QCoreApplication::applicationDirPath()).filePath("qml"));
QString arcGISRuntimeImportPath = QUOTE(ARCGIS_RUNTIME_IMPORT_PATH);
#if defined(LINUX_PLATFORM_REPLACEMENT) // on some linux platforms the string 'linux' is replaced with 1 // fix the replacement paths which were created QString replaceString = QUOTE(LINUX_PLATFORM_REPLACEMENT); arcGISRuntimeImportPath = arcGISRuntimeImportPath.replace(replaceString, "linux", Qt::CaseSensitive); #endif
// Add the Runtime and Extras path view.engine()->addImportPath(arcGISRuntimeImportPath);
// Set the source view.setSource(QUrl("qrc:/Samples/Layers/RasterColormapRenderer/RasterColormapRenderer.qml"));
view.show();
return app.exec();}