Reference:
http://wiki.openstreetmap.org/wiki/ Slippy_map_tilenames#Zoom_levels
Brief overview:
OSM tiles are 256x256 pixel PNG files.
Filename (URL) format is http://tile.openstreetmap.org/zoom/x/y.png
where
zoom=zoom-level-integer (from 0 to 19),
x=longitude-locator-integer (non-negative column number),
y=latitude-locator-integer (non-negative row number).
In the link above, see sample code to calculate x and y for a given zoom-level and a given latitude and longitude.
The following Atlanta GA area map is done
with map tiles at OSM zoom level 12.
Approximate latitude,longitude of Atlanta area:
33.755, -84.390 degrees
Each OSM tile is a 256x256 PNG file.
Each zoom-level-12 tile is one image of
2^12 x 2^12 = 4096 x 4096 = 16,777,216 images ~ 16 million images
which are used by OpenStreetMap to cover most of the Earth.
These zoom-level-12 tiles go from
x-numbers 1084 to 1090. (7 columns)
These zoom-level-12 tiles go from
y-numbers 1636 to 1642. (7 rows)
Total: 7 x 7 = 49 tiles
Image width: 7 x 256 = 1,792 pixels
Image height: 7 x 256 = 1,792 pixels
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Here is a link to the OSM (openstreetmap.org)
'slippy map'
for
Atlanta, Georgia (Wikipedia link) --- initially at zoom-level 12 and
centered at latitude and longitude 33.7500 -84.3833.
Page was created 2016 Oct 30.
Page was chnaged 2018 Jul 08.
(Added 'slippy map' link.)
Page was changed 2019 Jan 11.
(Added css and javascript to try to handle text-size
for smartphones, esp. in portrait orientation.)
Page was changed 2019 Feb 10.
(HTML changes due to reorg of OSMmaps.)