By Jonathan Cohen, Eduardo Poyart, and Cris Castello, Software Engineers, Google Earth
Google Earth has always presented a compelling view of the planet’s surface, cities and surroundings. And today, we’re excited to take this idea one step further with a new way to see the dynamic nature of our changing planet. We are introducing animated clouds in Google Earth for Chrome, which showcases the last 24 hours of weather patterns around the globe.
To try it, go to Map Styles in the menu and toggle on the “Animated Clouds” option. Make sure you’re zoomed out to space and watch the clouds loop on a 24-hour window. As you zoom closer to Earth, the clouds fade out to provide an unobstructed view of the ground.
Where the cloud data comes from
The cloud data you see in Google Earth is a mosaic of seven individual satellite images, put together by the U.S. Naval Research Laboratory. We get a new one of these images roughly once an hour, though it may be a few hours old by the time you see it in Earth.
The complete cloud image provided to Google by NRL is 9000x4500 pixels — that’s about 40 million pixels, or megapixels. At Google, we perform some additional processing to prepare it for use in Earth. Using Google Earth Engine, we smooth out some of the hour-to-hour changes, add visual shadowing effects to enhance the appearance, and export a 24-hour period to our own scalable video format.
How we render animated clouds
The entire cloud video that covers Google Earth is 40 megapixels. That’s 20 times higher resolution than an HD video (1080p), or five times higher resolution than a UHD video (ultra-high definition, or 4k). Fortunately, we don’t need to decode and render all those pixels for every view you see in Earth. Our scalable video format supports downloading, decoding and rendering just the pixels needed for your current view of the Earth, at a resolution appropriate for your screen and zoom level.
We display the clouds at a comfortable animation rate of one frame per second, corresponding to one hour of cloud motion time per second in Google Earth, with smooth blending (or cross-fading) between successive frames of the video. One novel feature of the cloud videos is that they include an alpha channel, allowing them to layer transparently on top of Earth.
More videos to come
Animated clouds is Google Earth’s first foray into presenting high-resolution video layers directly on the Earth. It is currently available on Google Earth for Chrome, but we expect to make it available soon on Earth for Android and iOS. As we continue to generalize and optimize our video infrastructure, we hope to increasingly use video map layers to enhance our ability to see and understand the dynamic stories of our planet.