Use a stretch renderer to enhance the visual contrast of raster data for analysis.
Use case
An appropriate stretch renderer can enhance the contrast of raster imagery, allowing the user to control how their data is displayed for efficient imagery analysis.
How to use the sample
Click 'Edit Renderer' to open the stretch renderer options. Choose one of the stretch parameter types:
- Standard deviation - a linear stretch defined by the standard deviation of the pixel values
- Min-max - a linear stretch based on minimum and maximum pixel values
- Percent clip - a linear stretch between the defined percent clip minimum and percent clip maximum pixel values
Then configure the parameters and click 'Render'.
How it works
- Create a
Raster
from a raster file. - Create a
RasterLayer
from theRaster
. - Add the layer to the map.
- Create a
StretchRenderer
, specifying the stretch parameters and other properties. - Set the
Renderer
on theRasterLayer
withrasterLayer::setRenderer(renderer)
.
Relevant API
- ColorRamp
- MinMaxStretchParameters
- PercentClipStretchParameters
- Raster
- RasterLayer
- StandardDeviationStretchParameters
- StretchParameters
- StretchRenderer
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
This sample uses a raster imagery tile of an area of forested mountainous terrain and rivers.
Additional information
See Stretch function in the ArcMap documentation for more information about the types of stretches that can be performed.
Tags
analysis, deviation, histogram, imagery, interpretation, min-max, percent clip, pixel, raster, stretch, symbology, visualization
Sample Code
// [WriteFile Name=RasterStretchRenderer, 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 "RasterStretchRenderer.h"
#include "Map.h"
#include "MapQuickView.h"
#include "MinMaxStretchParameters.h"
#include "PercentClipStretchParameters.h"
#include "Raster.h"
#include "RasterLayer.h"
#include "StretchRenderer.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
RasterStretchRenderer::RasterStretchRenderer(QQuickItem* parent /* = nullptr */):
QQuickItem(parent),
m_dataPath(defaultDataPath() + "/ArcGIS/Runtime/Data/raster")
{
}
RasterStretchRenderer::~RasterStretchRenderer() = default;
void RasterStretchRenderer::init()
{
// Register the map view for QML
qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
qmlRegisterType<RasterStretchRenderer>("Esri.Samples", 1, 0, "RasterStretchRendererSample");
}
void RasterStretchRenderer::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);
}
//! [RasterStretchRenderer cpp set renderers]
void RasterStretchRenderer::applyMinMax(double min, double max)
{
MinMaxStretchParameters stretchParams(QList<double>{min}, QList<double>{max});
QList<double> gammas;
bool estimateStats = true;
StretchRenderer* renderer = new StretchRenderer(stretchParams, gammas, estimateStats, PresetColorRampType::None, this);
m_rasterLayer->setRenderer(renderer);
}
void RasterStretchRenderer::applyPercentClip(double min, double max)
{
PercentClipStretchParameters stretchParams(min, max);
QList<double> gammas;
bool estimateStats = true;
StretchRenderer* renderer = new StretchRenderer(stretchParams, gammas, estimateStats, PresetColorRampType::None, this);
m_rasterLayer->setRenderer(renderer);
}
void RasterStretchRenderer::applyStandardDeviation(double factor)
{
StandardDeviationStretchParameters stretchParams(factor);
QList<double> gammas;
bool estimateStats = true;
StretchRenderer* renderer = new StretchRenderer(stretchParams, gammas, estimateStats, PresetColorRampType::None, this);
m_rasterLayer->setRenderer(renderer);
}
//! [RasterStretchRenderer cpp set renderers]