Geodesic operations

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Calculate a geodesic path between two points and measure its distance.

screenshot

Use case

A geodesic distance provides an accurate, real-world distance between two points. Visualizing flight paths between cities is a common example of a geodesic operation since the flight path between two airports takes into account the curvature of the earth, rather than following the planar path between those points, which appears as a straight line on a projected map.

How to use the sample

Click anywhere on the map. A line graphic will display the geodesic line between the two points. In addition, text that indicates the geodesic distance between the two points will be updated. Click elsewhere and a new line will be created.

How it works

  1. Create a Point in New York City and display it as a Graphic.
  2. Obtain a new point when a click occurs on the MapView and add this point as a graphic.
  3. Create a Polyline from the two points.
  4. Execute GeometryEngine::densifyGeodetic by passing in the created polyine then create a graphic from the returned Geometry.
  5. Execute GeometryEngine::lengthGeodetic by passing in the two points and display the returned length on the screen.

Relevant API

  • GeometryEngine::densifyGeodetic
  • GeometryEngine::lengthGeodetic

About the data

The Imagery basemap provides the global context for the displayed geodesic line.

Tags

densify, distance, geodesic, geodetic

Sample Code

GeodesicOperations.qmlGeodesicOperations.cppGeodesicOperations.h
                                              
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// [WriteFile Name=GeodesicOperations, Category=Geometry]
// [Legal]
// Copyright 2018 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

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

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

    // display text for geodesic length
    Text {
        anchors {
            left: parent.left
            top: parent.top
            margins: 10
        }

        text: "%1 kilometers".arg(distanceText)
        visible: distanceText.length > 0
        font.pixelSize: 20
        color: "white"
    }
}

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