Once you create an overlay, it has many of the same features available to it as a simple placemark. With overlays, you can:
- Email them to other people - You can email image overlays just as you would mail other placemark data. However, keep in mind that overlay files can only be opened by other users of Google Earth. If you want to send the overlay image as it appears on the earth to someone who doesn't have Google Earth, email the view instead. For details on emailing overlays, see Emailing Places Data.
When you email an overlay that references a local image, that image is automatically included with the overlay. You do not need to include the local image in your email attachment. This is an upgrade from Google Earth (Keyhole) version 2.2 and earlier.
- Save them to your computer. See Saving Places Data for details.
- Edit their properties and settings - See Editing Places and Folders for relevant information.
In addition to common placemark features, image overlays also have the following features:
Transparency Adjustment - You can adjust the transparency of an overlay from completely transparent to fully opaque whenever it is selected in the viewer. By adjusting the transparency of the overlay image, you can see how the overlay image corresponds to the 3D viewer imagery beneath.
- Overview slider for selected overlay
When you create an overlay, it completely integrates with the terrain or shape of the land beneath if the terrain layer is turned on. For example, you might create an overlay of Yosemite National Park and be able to view the trails in relationship to the 3D view of the mountains. In this way, the combination of an overlay map and the 3D viewer imagery gives more information than either one by itself.
Overlay map with terrain off
Overlay map with terrain on
- Updates based on time or view coordinates - If you are viewing time-sensitive imagery that changes periodically, you can set the imagery to a refresh rate to make sure you are viewing the latest image. This is useful for viewing imagery maps from the web where the image is automatically updated.
In addition, you can set the imagery to update depending upon your view. For example, you might be viewing imagery from a server that only delivers imagery that can be seen in your current 3D view. In this case, the imagery update changes whenever you navigate the 3D viewer to a new position.
- Draw Order - You can determine the hierarchy Google Earth uses when you use overlapping image overlays. Google Earth displays images with a higher draw order number in front of images with a lower draw number.
This section covers three parts to creating an image overlay:
- Position the 3D viewer in the location where you want to place the overlay image file.
Try to position the viewer so that it corresponds in viewing altitude to the overlay. If the overlay is of a detailed view, zoom into the subject area so that you don't have to make large adjustments later. By contrast, if the overlay covers a large area, make sure the entire area is encompassed in the 3D viewer with some margins for adjusting the imagery.
- Click Add > Image Overlay or click . The 'New Image Overlay' dialog box appears.
- Provide a descriptive name in the Name field.
- In the Link field, enter the location of the image file you want to use as an overlay or use the Browse button to locate it on your computer or network.
- If the image you are referencing is located on the Internet, you will need to enter the URL for that image file. This is different from the URL for the web page itself! If you are using Internet Explorer, you can retrieve the URL for an image by right-clicking on the image on its web page and selecting Copy Shortcut from the pop-up menu. At that point, you can insert your cursor in the 'Image URL' or 'Filename' field and paste the information using CTRL+V ( on the Mac).
The image appears in the 3D viewer, with anchor points that you use to position it.
- Specify the descriptive information for the overlay. Descriptions for overlays are identical to descriptions for all places data.
- Click the Refresh tab and set the correct refresh properties for your overlay imagery. The refresh settings for overlays are identical to those described for network links. Typically, any imagery that is updated automatically and located on a server will need refresh properties set. For example, weather satellite image maps will likely need to be refreshed. For details on the differences between time-based and view-based refresh, see the description for network links.
- Set the default transparency for the imagery using the slider. The transparency setting for image overlays can be adjusted at any time when you are viewing an overlay. To make it easy to position the overlay, first adjust the transparency to achieve a good balance between seeing the imagery and the earth beneath it.
- When you select the View tab, you can modify the view settings for the overlay just as you would any place data. See Setting the View for details.
- Position the image in the viewer to your preferences and click OK to complete the creation. If you later want to correct the overlay or reposition it, simply edit the overlay as you would any other places data. See the topics in Editing Places and Folders for more information.
Once you have inserted the overlay image into the viewer, you can use the green markers to stretch and move the image in a number of ways to get the most exact positioning required. An overlay image will have corner and edge marks that you can use to stretch the image, a central cross hair marker to position the image, and a triangle marker that you can use to rotate the image.
When you select one of these markers, the cursor changes from an open hand to either a finger-pointing hand or an arrow to indicate that an anchor point is selected. The following illustration describes the anchor points in detail.
- Use the center cross-hair marker to slide the entire overlay on the globe and position it from the center. (Tip: do this first.)
- Use the triangle marker to rotate the image for better placement.
- Use any of the corner cross-hair markers to stretch or skew the selected corner. If you press the Shift key when selecting this marker, the image is scaled from the center.
- Use any of the four side anchors to stretch the image in or out of from the selected side. If you press the Shift key when doing this, the image is scaled from the center.
When you select the 'Location' tab, you can use the following settings:
- Manual coordinates for each corner of the image overlay. This is similar in principle to the manual setting discussed in Repositioning Placemarks, except that instead of setting coordinates for a single point, you set coordinates for each corner of the image overlay. You might want to use this feature if your image overlay comes from a precise map where the exact coordinates are known.
- Draw Order - If you have more than one overlay for a given region, you can set the draw order for overlays to determine which image is displayed relative to other images. Overlays with higher numbers are drawn before those with lower numbers.
- Fit to Screen - Click this to resize the image to fit the current view.
When you select the View tab, you can modify the view settings for the overlay just as you would any place data. See Setting the View for details.