The underlying basemap used by NYCityMap are pre-generated map images (i.e., map tiles) that comprise a tile set. Each zoom level (i.e., hash mark on the zoom slider) has it’s own set of tiles at that specific scale. The NYCityMap tile set is shared by other mapping applications for efficiency and consistency of look and feel. In total, the NYCityMap tile set is comprised of 2,003,057 number of map tiles totaling approximately 16 GB.
Using map tiles has become the industry standard. Maps are composed from a grid of image tiles. The grid extends beyond the viewable area so that users can pan without the need to retrieve additional tiles. Breaking the map up into smaller sections also allows the browser to download those images more quickly than a single giant map image. When a user pans out of range the browser only needs to download a few new tiles to fill in the view.
The below examples show some of the updates made in the new tile set. These included updated data and improved labeling.