Ground overlays are image overlays that are tied to latitude/longitude coordinates, so they move when you drag or zoom the map.
The ApiDemos repository on GitHub includes a sample that demonstrates ground overlays:
- GroundOverlayDemoActivity: Ground overlay features and listeners
A ground overlay is an image that is fixed to a map. Unlike markers, ground overlays are oriented against the Earth's surface rather than the screen, so rotating, tilting or zooming the map will change the orientation of the image. Ground overlays are useful when you wish to fix a single image at one area on the map. If you want to add extensive imagery that covers a large portion of the map, you should consider a Tile overlay.
Add an overlay
To add a
GroundOverlay, create a
GroundOverlayOptions object that defines both an
image and a position. You can optionally specify additional settings that will
affect the positioning of the image on the map. Once you've defined the
necessary options, pass the object to the
method to add the image to the map. The
addGroundOverlay() method returns a
GroundOverlay object; you should retain a reference to
this object if you want to modify it later.
Step by step:
- Instantiate a new
- Specify the image as a
- Set the position of the image using one of the available methods:
position(LatLng location, float width, float height)
position(LatLng location, float width)
- Set any optional properties, such as
transparency, as desired.
GoogleMap.addGroundOverlay()to add the image to the map.
The below example demonstrates how to add a ground overlay to an existing
LatLng NEWARK = new LatLng(40.714086, -74.228697); GroundOverlayOptions newarkMap = new GroundOverlayOptions() .image(BitmapDescriptorFactory.fromResource(R.drawable.newark_nj_1922)) .position(NEWARK, 8600f, 6500f); map.addGroundOverlay(newarkMap);
If you wish to change or remove a ground overlay after you've added it to
the map, ensure that you keep hold of the
GroundOverlay object. You can
modify the overlay later by making changes to this object.
LatLng NEWARK = new LatLng(40.714086, -74.228697); GroundOverlayOptions newarkMap = new GroundOverlayOptions() .image(BitmapDescriptorFactory.fromResource(R.drawable.newark_nj_1922)) .position(NEWARK, 8600f, 6500f); // Add an overlay to the map, retaining a handle to the GroundOverlay object. GroundOverlay imageOverlay = map.addGroundOverlay(newarkMap);
Remove an overlay
You can remove a ground overlay with the
Change an overlay
You can change the ground overlay image after it's been added to the map with
// Add an overlay, retaining a handle to the GroundOverlay object. GroundOverlay imageOverlay = map.addGroundOverlay(newarkMap); // Update the GroundOverlay with a new image of the same dimensions. imageOverlay = map.setImage(BitmapDescriptorFactory.fromResource(R.drawable.newark_nj_1975));
setImage() method will replace the existing image with another image of
the same dimensions.
Position a Ground Overlay
There are two ways to specify the position of the ground overlay:
- Using a
LatLngto center the overlay, and dimensions in meters to specify the size of the image.
- Using a
LatLngBoundsto specify the north east and south west corners of the image.
You must specify the position of the ground overlay before it is added to the map.
Use location to position an image
When you add the image you specify a LatLng to which the anchor will be fixed
and the width of the overlay (in meters). The
anchor defaults to the center of the
image. You can optionally provide the height of the overlay (in meters). If
you do not provide the height of the overlay, it will be automatically
calculated to preserve the proportions of the image.
The below code places an image at position
that is 8.6km wide by 6.5km high. The image is anchored at the bottom left.
GroundOverlayOptions newarkMap = new GroundOverlayOptions() .image(BitmapDescriptorFactory.fromResource(R.drawable.newark_nj_1922)) .anchor(0, 1) .position(new LatLng(40.714086, -74.228697), 8600f, 6500f);
Use LatLngBounds to position an image
You provide a
LatLngBounds which contains the image. The
LatLngBounds sets the north east, and south west corners of the image. When
the image is drawn on the map it will be rotated to fit the bounds. If the
bounds do not match the original aspect ratio, the image will be skewed.
The below code places an image on the map with its South West corner bound to
40.712216,-74.22655 and its North East corner bound to
LatLngBounds newarkBounds = new LatLngBounds( new LatLng(40.712216, -74.22655), // South west corner new LatLng(40.773941, -74.12544)); // North east corner GroundOverlayOptions newarkMap = new GroundOverlayOptions() .image(BitmapDescriptorFactory.fromResource(R.drawable.newark_nj_1922)) .positionFromBounds(newarkBounds);
Associate data with a ground overlay
The following code sample stores a string description with a ground overlay:
private GoogleMap mMap; private GroundOverlay mSydneyGroundOverlay; mSydneyGroundOverlay = mMap.addGroundOverlay(new GroundOverlayOptions() .image(BitmapDescriptorFactory.fromResource(R.drawable.harbour_bridge)) .position(new LatLng(-33.873, 151.206)) .clickable(true)); mSydneyGroundOverlay.setTag("Sydney");
Here are some examples of scenarios when it's useful to store and retrieve data with ground overlays:
- Your app may cater for different ground overlays, and you want to treat them differently when the user clicks them.
- You may be interfacing with a system that has unique record identifiers, where the overlays represent specific records in that system.
- The overlay data may indicate a priority to determine the z-index for the overlay.
Handle ground overlay events
By default, ground overlays are
not clickable. You can enable and disable the clickability by calling
to listen to click events on a clickable ground overlay. To set this listener on
the map, call
When a user clicks on a ground overlay, you will receive an