I don't know a lot about google maps, but I worked on the zoomable image formats used in Google Arts and Culture. It's quite interesting, because they tried to prevent the image tiles from being downloaded by signing tile URLs and encrypting the JPEG images. I think there is a lot to learn about the format by reading the sources of dezoomify :
- https://github.com/lovasoa/dezoomify/blob/master/dezoomers/g...
- https://github.com/lovasoa/dezoomify/blob/master/dezoomers/g...