It’s a fascinating view of where people tweet – the major CBD’s are focal points obviously but so are several tourist spots. The straight lines on the left of the picture are from people tweeting from the ferry. There’s a potentially concerning level of tweets from the main roads too.
The detail on the original image is high enough that I think I can spot my house.
If you find the geography confusing, some clever person has also superimposed the image onto a Google map.
Thanks to Reddit for the original source.