Are Google Earth Images In Real-Time?

A look at Earth images
Images on Earth are highly detailed but do not show imagery in real-time.
Many people according to Frank Taylor at his Earth Blog believe the images are in real time. He believes that is because of weather satellite photos that are a few hours old or because of live weather radar. He goes into detail how Google collects its images for Google Earth.
Taylor writes, “High resolution satellites (like those operated by DigitalGlobe) operate just a few hundred kilometers above the Earth. This means they only see a small part of the Earth with their camera as they orbit over.”
“They typically go around the Earth every 90 minutes, but only cover about 1% of the Earth on each pass (you can see strips of imagery if you look at the imagery in Earth) – most of that is water.”
One reason why the images are not in real time is that they must be processed by a commercial provider like DigitalGlobe before being passed on to Google. Goggle then compares the imagery to the current imagery to see if the new imagery is better than the current.
Taylor writes,” Once an image is selected, it has to be processed into the format and coordinate system of Earth’s databases. Then it has to go through a quality control process and fed into a processing system before it gets distributed to the live Google Earth database servers.”
Another reason there is not newer imagery according to Taylor is that it is expensive to purchase quality aerial imagery. Taylor points out that recent imagery is worth more than older imagery and companies do not want to have their newest imagery available for free on Earth. He says you cannot sell or use the imagery from Google Earth for business purposes without permission.
There is near real- time imagery of Earth available on Earth. Taylor writes,” first there’s the new Clouds layer. Found under the new Weather layer folder. The clouds are actually taken from weather satellites and are a global picture of the clouds as recent as 3 hours old.”
He also points to NASA. “NASA has a layer they call DailyPlanet which shows the entire Earth at a medium resolution (about 500 meter resolution per pixel). You can view DailyPlanet in Earth.”
“Right now, this layer from NASA is the most recent, highest resolution imagery of the Earth continuously updating available to the general public.”
By Mike Sachoff – Fri, 02/08/2008 -

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