Display a raster on a map and apply different rendering rules to that raster.
Use case
Raster images whose individual pixels represent elevation values can be rendered in a number of different ways, including representation of slope, aspect, hillshade, and shaded relief. Applying these different rendering rules to the same raster allows for a powerful visual analysis of the data. For example, a geologist could interrogate the raster image to map subtle geological features on a landscape, which may become apparent only through comparing the raster when rendered using several different rules.
How to use the sample
Run the sample and use the drop-down menu at the top to select a rendering rule.
How it works
When the sample starts, an ImageServiceRaster is created and added to a RasterLayer. The RasterLayer is then added to the map as an operational layer. Connect to the loadStatusChanged signal for the ImageServiceRaster. Once the ImageServiceRaster is loaded, the RenderingRuleInfos are fetched. Iterate over each item in the RenderingRuleInfos to get the rendering rule name and populate a data model using the names. This becomes the model for the combo box. When an item from the combo is selected and apply is pressed, the RenderingRuleInfo for the selected index is fetched from the service info. A RenderingRule object is created using the RenderingRuleInfo and applied to a newly created ImageServiceRaster. The ImageServiceRaster is then added to the RasterLayer.
- Create an
ImageServiceRasterusing a URL to an online image service. - After loading the raster, use
imageServiceRaster.serviceInfo.renderingRuleInfosto get a list ofRenderingRuleInfosupported by the service. - Choose a rendering rule info to apply and use it to create a
RenderingRule. - Create a new
ImageServiceRasterusing the same URL. - Apply the rendering rule to the new raster by setting
imageServiceRaster.renderingRule = renderingRule. - Create a
RasterLayerfrom the raster for display.
Relevant API
- ImageServiceRaster
- RasterLayer
- RenderingRule
About the data
This raster image service contains 9 LAS files covering Charlotte, North Carolina's downtown area. The lidar data was collected in 2007. Four Raster Rules are available for selection: None, RFTAspectColor, RFTHillshade, and RFTShadedReliefElevationColorRamp.
Additional information
Image service rasters of any type can have rendering rules applied to them; they need not necessarily be elevation rasters. See the list of raster function objects and syntax for rendering rules in the ArcGIS REST API documentation.
Tags
raster, rendering rules, visualization
Sample Code
// [WriteFile Name=RasterRenderingRule, 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 QtQuick
import QtQuick.Controls
import QtQuick.Layouts
import Esri.ArcGISRuntime
import Esri.ArcGISExtras
Rectangle {
id: rootRectangle
clip: true
width: 800
height: 600
property var renderingRuleNames: []
readonly property url imageServiceUrl: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/CharlotteLAS/ImageServer"
MapView {
id: mapView
anchors.fill: parent
Component.onCompleted: {
// Set the focus on MapView to initially enable keyboard navigation
forceActiveFocus();
}
Map {
id: map
// create a basemap from a tiled layer and add to the map
Basemap {
initStyle: Enums.BasemapStyleArcGISStreets
}
//! [RasterRenderingRule qml ImageServiceRaster]
// create and add a raster layer to the map
RasterLayer {
// create the raster layer from an image service raster
ImageServiceRaster {
id: imageServiceRaster
url: imageServiceUrl
// zoom to the extent of the raster once it's loaded
onLoadStatusChanged: {
if (loadStatus === Enums.LoadStatusLoaded) {
mapView.setViewpointGeometry(imageServiceRaster.serviceInfo.fullExtent);
const renderingRuleInfos = imageServiceRaster.serviceInfo.renderingRuleInfos;
const names = [];
for (let i = 0; i < renderingRuleInfos.length; i++) {
names.push(renderingRuleInfos[i].name);
}
renderingRuleNames = names;
}
}
}
}
//! [RasterRenderingRule qml ImageServiceRaster]
}
Rectangle {
anchors {
left: parent.left
top: parent.top
margins: 5
}
height: childrenRect.height
width: childrenRect.width
color: "silver"
radius: 5
GridLayout {
columns: 2
Label {
Layout.margins: 10
Layout.columnSpan: 2
Layout.alignment: Qt.AlignHCenter
text: "Apply a Rendering Rule"
font.pixelSize: 16
}
ComboBox {
id: renderingRulesCombo
property int modelWidth: 0
Layout.minimumWidth: modelWidth + leftPadding + rightPadding + (indicator ? indicator.width : 10)
model: renderingRuleNames
onModelChanged: {
for (let i = 0; i < model.length; ++i) {
metrics.text = model[i];
modelWidth = Math.max(modelWidth, metrics.width);
}
}
TextMetrics {
id: metrics
font: renderingRulesCombo.font
}
}
Button {
id: applyButton
Layout.margins: 10
text: "Apply"
onClicked: {
applyRenderingRule(renderingRulesCombo.currentIndex);
}
}
}
}
}
function applyRenderingRule(index) {
//! [ImageServiceRaster Create a rendering rule]
// get the rendering rule info at the selected index
const renderingRuleInfo = imageServiceRaster.serviceInfo.renderingRuleInfos[index];
// create a rendering rule object using the rendering rule info
const renderingRule = ArcGISRuntimeEnvironment.createObject("RenderingRule", {renderingRuleInfo: renderingRuleInfo});
// create a new image service raster
const newImageServiceRaster = ArcGISRuntimeEnvironment.createObject("ImageServiceRaster", {url: imageServiceUrl});
// apply the rendering rule
newImageServiceRaster.renderingRule = renderingRule;
// create a raster layer using the image service raster
const rasterLayer = ArcGISRuntimeEnvironment.createObject("RasterLayer", {raster: newImageServiceRaster});
//! [ImageServiceRaster Create a rendering rule]
// add the raster layer to the map
map.operationalLayers.append(rasterLayer);
}
}