This is the first in a series of posts on animating in Google Earth. It is generally well known that Google Earth can display 3D models provided in KML files. Less well known is that it is possible to do basic animation in Google Earth. We have looked at a number of amazing Google Earth animations over the years, but relative to the other content for Google Earth, animations are extremely rare. There are a number of reasons for this, including a lack of good information regarding how to create these animations and easy to use tooling.
Today we are exploring the three main types of animation and their pros and cons.
In general, none of the animation methods are trivial, and almost all require some programming knowledge or custom tools to achieve a reasonable animation. Google does not provide any tools for creating animations but they do provide basic documentation for each mechanism.
Google Earth tours provide a mechanism for animating models. The animations are defined within the KML as documented here. Although KML can be typed out by hand this is completely impractical and it is necessary to have a tool that generates the KML as required.
– The person creating the tour has near complete control over what the user sees. This can be useful as it is quite easy to loose track of a moving model in Google Earth.
– Smooth animations along a line or constant rotation are handled automatically and need a lot less lines of KML than the time-based method.
– The complete control by the tour creator comes at the cost of practically no control by the user. The tour can be paused so the user can look around, but the user cannot change the view much while the tour is playing so live animations cannot be fully explored.
When to use
This is best used for models that move over a long distance that the viewer would easily lose track of. It is also ideal when you want to include other information that is best suited to being presented in a tour.
Steven Ho’s Maokong Gondola of Taipei
To see it in Google Earth, download the KML from Steven’s blog.
This uses the Google Earth time toolbar in conjunction with time stamps in a KML file. The relevant KML documentation can be found here.
– This technique does not take control of the user’s view point so they are free to move around and look at the animation from different angles.
– It does not have a smooth animation feature, so smooth animations require a lot of frames, which results in very large KML files for long animations.
– The time toolbar can be confusing and users may not even realise that they must use it to view the animation. In addition, the speed of the animation is set by the user, and achieving a specific speed is difficult.
When to use
This is best suited to short, repeating animations.
The London Eye animation by Barnabu.
Turn off the Google Earth 3D buildings layer for best results.
This technique is also used for animations that do not involve models, such as the USGS animated KMLs showing earthquakes over time.
Google Earth API
This provides the greatest level of control and allows very complex animations.
The Google Earth API has been deprecated and could be shut down at any time. In addition, it is only supported in a few browsers (Firefox for example).
The Monster Milktruck consists of a driving simulator in Google Earth.