The HERE SDK provides a number of ways to change the view on a map. While you can use map styles to change the look of the map, you can use a camera to view the map from different perspectives.
For example, the HERE SDK allows you to set a target location, tilt the camera, zoom in and out, or set a bearing angle.
At a glance
- Use the
mapView.getCamera()to manipulate the view of the map.
- Set a new target location by calling
camera.lookAt(new GeoCoordinates(52.530932, 13.384915)).
- Zoom the map by setting a distance in meters:
camera.lookAt(new GeoCoordinates(52.530932, 13.384915), distanceInMeters).
- Set a
MapCamera.OrientationUpdate()to specify the tilt angle and bearing angle of the camera.
- Set the bounds of the currently displayed area by calling
camera.lookAt(geoBox, new MapCamera.OrientationUpdate()).
By default, the camera is located centered above the map. From a bird's eye view looking straight-down, the map is oriented North-up. This means that on your device, the top edge is pointing to the north of the map.
With the camera, you cannot rotate the map directly, but change the camera's orientation instead. By changing the
bearing parameter of the
MapCamera.OrientationUpdate(), you will have the same effect as when rotating the map.
The orientation of the map is usually specified by a bearing angle. 'Bearing' is a navigation term, counted in degrees, from the North in a clockwise direction.
By default, the camera has a bearing value of 0° degrees. By setting a bearing angle of 45°, as visualized in the illustration above, the map appears to the camera's eye as it rotates counter-clockwise and the direction of the bearing becomes the new upward direction on your map, pointing to the top edge of your device. This is similar to holding and rotating a paper map while hiking in a certain direction. Apparently, it is easier to orient yourself if the map's top edge points in the direction in which you want to go. However, this will not always be the true North direction (bearing = 0°).
Note that the bearing axis is always perpendicular to the ground and passes through the camera, regardless of the current camera orientation.
The following code rotates the camera by 90°:
double bearingInDegress = 90; double tiltInDegress = 0; MapCamera.OrientationUpdate orientation = new MapCamera.OrientationUpdate(bearingInDegress, tiltInDegress); double distanceInMeters = 1000 * 7; mapView.getCamera().lookAt( new GeoCoordinates(52.373556, 13.114358), orientation, distanceInMeters);
Effectively, for the viewer this lets the map appear rotated by 90° to the left.
The camera can also be used to transform the flat 2D map surface to a 3D perspective to see, for example, roads at a greater distance that may appear towards the horizon. By default, the camera is not tilted (tilt = 0°).
In addition to the tilt value of the camera, the camera's bearing angle (see above) can be manipulated. Here we show the effect of changing the tilt value. Look at the illustration below to see the available camera axes.
A tilt value of 0° means that the camera's optical axis is perpendicular to the ground. The tilt angle is always calculated from this perpendicular axis. The tilt angle relates to the optical axis of the camera.
As visualized in the illustration, tilting the camera by 45° will change the bird's eye view of the camera to a 3D perspective. Use the code below to change only the tilt value of the camera:
double bearingInDegress = 0; double tiltInDegress = 45; MapCamera.OrientationUpdate orientation = new MapCamera.OrientationUpdate(bearingInDegress, tiltInDegress); double distanceInMeters = 1000 * 7; mapView.getCamera().lookAt( new GeoCoordinates(52.373556, 13.114358), orientation, distanceInMeters);
Any subsequent tilt value will always be applied from the camera's default location. This is the same for the tilt angle and the bearing angle of the camera. Some values will be clamped when they are out of range.
All axes can be manipulated at the same time. Changing the bearing value will give different results when the camera is tilted.
By setting a new camera target, you can change the camera's location and effectively change the location that is shown at the center of the map view. The
lookAt() method is available in different overloads. Just a few examples:
// Change only the location. camera.lookAt(new GeoCoordinates(52.530932, 13.384915)); // Change zoom and location. double distanceInMeters = 1000 * 2; camera.lookAt(new GeoCoordinates(52.530932, 13.384915), distanceInMeters); // Change location area and orientation. GeoBox geoBox = new GeoBox(new GeoCoordinates(52.373556, 13.114358), new GeoCoordinates(52.611022, 13.479493)); double bearingInDegress = 0; double tiltInDegress = 45; MapCamera.OrientationUpdate orientation = new MapCamera.OrientationUpdate(bearingInDegress, tiltInDegress); camera.lookAt(geoBox, orientation);
Note that changing the orientation (bearing, tilt) of the camera does not change the location of the map.
By changing the camera, you can only programmatically change the perspective of the map view, but you do not have direct control of the map view itself - like when performing gestures to zoom the map or to rotate or to tilt the map. See the Gestures section for an overview of the available gestures to manipulate the map directly.