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Blue Sky vs. Gray Sky collections: Blue Sky collections are represented with a blue circle. Dark blue represents Urban collections at higher resolutions. Light blue represents Wide Area collections with a slightly lower resolution. Gray Sky collections are represented with a gray storm cloud.
2D collection vs. 3D collections: The 2D and 3D designations on the timeline stops indicate whether the given collection is 2D only or whether it’s a collection that includes 3D.
Collection date: The collection year is shown over the first collection in the given year. The full date for any collection can be seen by hovering over it or clicking on it to select it.
Currently visible collection: The white arrow indicates which collection is currently selected/visible on the map.
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