You can change altitude settings in the Altitude tab of the 'Edit Placemark/Folder' dialog box (Edit > Properties). Altitude values can be set on a single item, across all items in a folder using shared styles, or using a mixture of altitude settings for items in a folder. Unlike other shared elements, modifying one item in a folder does not disable the shared style feature for other elements such as color and scale. If your folder contains items with different altitude settings, the parent folder indicates 'Mixed Modes' as the altitude settings.
Finally, you can use the values set in the 'Altitude' area to extrude geometry.
There are five options for altitude:
- Clamped to ground - By default, all folders and placemarks are set to this option. Here, because the altitude for the placemark is locked to the ground, no height value is allowed for altitude. This ensures that the placemark remains fixed to the earth, regardless of whether terrain is on or off.
- Clamped to sea floor - This option is similiar to clamped to ground, the only difference is that the placemark is locked to the sea floor.
- Relative to ground - When this option is selected, altitude of the placemark is relative to the actual ground elevation of the view. For example, if you set 9 meters as the altitude of a placemark in Venice, Italy, the elevation of the placemark will be 9 meters above the ground because Venice is at sea level. However, if you set the same placemark above Denver, Colorado, the elevation of the placemark will be 1616 meters, because the elevation of Denver is 1607 meters. You can see this how this appears in the 3D viewer by setting elevation, tilting the view, and turning terrain on and off.
- Relative to sea floor - Again this option is very similiar to Relative to ground but the placemark is relative to the sea floor instead of the actual ground evelation of the view.
- Absolute - When this option is selected, altitude of the Placemark is above sea level. In the example above, if you have terrain on and keep altitude to 9 meters but set the altitude type to 'Absolute', the icon would disappear from view because it is actually below the level of the terrain at Denver, Colorado. You can adjust the altitude using the slider or by entering a value in meters in the 'Altitude' field.
Placemark over the Google campus with relative altitude set to nine meters, terrain off
Same placemark, terrain on
You can adjust the altitude using the slider or by entering a value in meters in the 'Altitude' field.
Once you set an altitude value for a folder or a placemark, you can check 'Extend to ground'. This draws a single line appears from the earth's surface to the placemark. When a line or a path is drawn with skirting, a geometric shape is drawn from the earth's surface to the path.