Raster function (service)

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Load a raster from a service, then apply a function to it.

screenshot

Use case

Raster functions allow processing operations that can be applied to one or more rasters on the fly. Functions can be applied to rasters that come from a service. A land survey agency may apply hillshade and aspect functions to rasters with elevation data in order to better determine the topography of a landscape and to make further planning decisions.

How to use the sample

The raster function is applied automatically when the sample starts and the result is displayed.

How it works

  1. Create the ImageServiceRaster referring to the image server URL.
  2. Create the RasterFunction from a JSON string.
  3. Set the raster argument with rasterFunction::setRaster(rasterName, imageServiceRaster).
  4. Create a new Raster referring to the raster function.
  5. Create a RasterLayer to visualize the computed raster.
  6. Display the raster.

Relevant API

  • ImageServiceRaster
  • Raster
  • RasterFunction
  • RasterFunctionArguments
  • RasterLayer

About the data

The sample applies a hillshade function to a raster produced from the National Land Cover Database, NLCDLandCover2001. You can learn more about the hillshade function in the ArcMap documentation.

Additional information

The raster function computation happens locally on the client device.

Tags

function, layer, raster, raster function, service

Sample Code

RasterFunctionService.qmlRasterFunctionService.cppRasterFunctionService.h
                                                                      
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// [WriteFile Name=RasterFunctionService, 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 2.6
import QtQuick.Controls 2.2
import Esri.Samples 1.0

RasterFunctionServiceSample {
    id: rootRectangle
    clip: true
    width: 800
    height: 600

    // add a mapView component
    MapView {
        anchors.fill: parent
        objectName: "mapView"
    }

    // Create a button to apply the raster function
    Rectangle {
        id: button
        property bool pressed: false

        anchors {
            right: parent.right
            bottom: parent.bottom
            rightMargin: 20
            bottomMargin: 40
        }

        width: 45
        height: width
        color: pressed ? "#959595" : "#D6D6D6"
        radius: 100
        border {
            color: "#585858"
            width: 1
        }

        Image {
            anchors {
                centerIn: parent
            }
            width: 26
            height: width
            source: "qrc:/Samples/Layers/RasterFunctionService/RasterImageAnalysisHillshade.png"
        }

        MouseArea {
            anchors.fill: parent
            onPressed: button.pressed = true
            onReleased: button.pressed = false
            onClicked: applyRasterFunction()
        }
    }
}

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