Project a point from one spatial reference to another.
Use case
Being able to project between spatial references is fundamental to a GIS. An example of when you would need to re-project data is if you had data in two different spatial references, but wanted to perform an intersect analysis with the GeometryEngine.intersect
function. This function takes two geometries as parameters, and both geometries must be in the same spatial reference. If they are not, you could first use GeometryEngine.project
to convert the geometries so they match.
How to use the sample
Click anywhere on the map. A callout will display the clicked location's coordinate in the original (basemap's) spatial reference and in the projected spatial reference.
How it works
- Call the static method,
GeometryEngine.project
, passing in the originalGeometry
and aSpatialReference
to which it should be projected.
Relevant API
- GeometryEngine
- Point
- SpatialReference
Additional information
In cases where the the output spatial reference uses a different geographic coordinate system than that of the input spatial reference, see the GeometryEngine.project method that additionally takes in a DatumTransformation parameter.
Tags
coordinate system, coordinates, latitude, longitude, projected, projection, spatial reference, Web Mercator, WGS 84
Sample Code
// [WriteFile Name=ProjectGeometry, 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 Esri.ArcGISRuntime 100.15
import Esri.ArcGISRuntime.Toolkit 100.15
Rectangle {
id: rootRectangle
clip: true
width: 800
height: 600
MapView {
id: mapView
anchors.fill: parent
Component.onCompleted: {
// Set the focus on MapView to initially enable keyboard navigation
forceActiveFocus();
}
Map {
Basemap {
initStyle: Enums.BasemapStyleArcGISTopographic
}
// Set initial viewpoint to Minneapolis
ViewpointExtent {
Envelope {
xMin: -10995912.335747
yMin: 5267868.874421
xMax: -9880363.974046
yMax: 5960699.183877
spatialReference: SpatialReference { wkid: 3857 }
}
}
}
// Declare a callout
Callout {
id: callout
calloutData: parent.calloutData
accessoryButtonHidden: true
autoAdjustWidth: true
maxWidth: 350
leaderPosition: leaderPositionEnum.Automatic
}
// create a graphics to show the input location
GraphicsOverlay {
// create a red marker symbol for the input point
Graphic {
id: inputGraphic
SimpleMarkerSymbol {
color: "red"
size: 5
style: Enums.SimpleMarkerSymbolStyleCircle
}
}
}
// handle mouseClicked signal
onMouseClicked: {
// get the mouse click as a point
const originalPoint = mouse.mapPoint;
// show the clicked location on the map with a graphic
inputGraphic.geometry = originalPoint;
// create the output SpatialReference by specifying a well known ID (WKID)
const spatialReference = ArcGISRuntimeEnvironment.createObject("SpatialReference", {
wkid: 4326
});
// project the web mercator point to WGS84
const projectedPoint = GeometryEngine.project(originalPoint, spatialReference);
// update callout data
calloutData.title = "Coordinates"
calloutData.location = originalPoint;
const ox = originalPoint.x.toFixed(5)
const oy = originalPoint.y.toFixed(5);
const px = projectedPoint.x.toFixed(5);
const py = projectedPoint.y.toFixed(5);
calloutData.detail = "Original: %1, %2\nProjected: %3, %4".arg(ox).arg(oy).arg(px).arg(py);
// show the callout
callout.showCallout();
}
}
}