The sequence of images below illustrates, in increasing complexity, the use of scripts to animate spatial pattern in Google Earth.
This image above is a really simple example. An image is constantly
(every 60 seconds) and overlain with a rectangular area. The tags <north>, <south>,
<east> and <west>
refer to the bounding box, not to the units. Thus, <east>-65</east>
means, that the eastern boundary of the image is 65° west of the
meridian. The image has to be transparent, so .PNG is a good file
format. You can check out the original image (it is
large: 6200x3000). Also, here is a link to the file radar.kml . Download the free Google Earth to view it.
This example is a little more complex. I started with a text description of all the points that I want to animate. The different components are separated by commas in anim.csv.
The format is pretty simple - the columns are: "time", "longitude", "latitude", "altitude", and "status". The status can be one of these elements ["green", "yellow", "red"].
It is important that you define the style of a <Placemark> before you use it. This is useful if the same style is needed for multiple <Placemark>. Here is the definition of one:
The track is just a special <Placemark> which uses the <LineString>. The <altitudeMode> describes if the points are relative to the ground or in absolute position. The <coordinates> can have the altitude as a third component and that attribute is measured in meters. The numbers have to be rather high (depending on your scale) to actually see the <Placemark> above the ground.
<coordinates>121.0,17.0 119.7,17.0 118.5,16.5 117.6,16.1 117.3,16.0 117.0,15.4 116.0,15.2 115.3,14.9 115.0,14.9 114.3,14.7 114.0,14.5 113.5,14.6 113.3,14.7 112.9,14.7 112.7,14.8 112.7,15.3 112.9,15.6 112.6,15.7 112.3,15.9 111.9,15.9 111.9,16.1 111.9,16.6 111.6,17.0 111.5,17.4 110.8,17.4 110.3,17.6 110.1,17.6 109.6,17.8 109.0,18.0 108.5,17.6 108.2,17.6 107.8,17.5 107.5,17.7 107.0,17.9 106.5,18.0 105.7,17.8 105.3,17.8 104.5,18.0 103.9,17.7 103.1,18.0 102.0,18.0</coordinates>
The animation points are pretty simple, too. Each point references a style. They also have a <TimeStamp> node in them, which activates Google Earth's animation slider.
The previous example used just one point in time for each <Placemark> by using <TimeStamp>. This example uses <TimeSpan> which allows a duration for a <Placemark>. This code anim.kml is still very simple:
Check out the mbus page for a real-time demonstration.
Check out the small WaterNow data set.
Scio Residents for Safe Water
Check out Scio Residents for Safe Water site for a pretty complex data set.