tmcw · February 11, 2026 06:42 · Feb 15, 2013 · Feb 15, 2013 · Feb 14, 2013 · Feb 14, 2013
diff --git a/xyz_vs_tms.md b/xyz_vs_tms.md
@@ -6,7 +6,7 @@ ending in `/0/0/0.png` or something. Sometimes if it's a script, it'll look like
 
 Good examples are OpenStreetMap, Google Maps, MapBox, MapQuest, etc. Lots of maps.
 
-Most of those are in XYZ. The best documentation for that is [slippy map tilenames](http://wiki.openstreetmap.org/wiki/slippy_map_tilenames) on the OSM Wiki.
+Most of those are in XYZ. The best documentation for that is [slippy map tilenames](http://wiki.openstreetmap.org/wiki/slippy_map_tilenames) on the OSM Wiki, and Klokan's [Tiles a la Google](http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/).
 
 Some of them are in TMS instead. TMS is an OSGeo spec. [Here's the wiki page on it](http://en.wikipedia.org/wiki/Tile_Map_Service). It's less popular and few services support the whole spec.
 

diff --git a/xyz_vs_tms.md b/xyz_vs_tms.md
@@ -18,7 +18,7 @@ Let's get to the point. The only difference between the two is a flipped y coord
 
 In math:
 
-    y = (2^z) - y - 1;
+    y = (2^z) - y - 1
 
 javascript
 
@@ -35,13 +35,13 @@ y = pow(2, z) - y - 1;
 python
 
 ```php
-y = (2 ** z) - y - 1;
+y = (2 ** z) - y - 1
 ```
 
 ruby
 
 ```ruby
-y = (2 ** z) - y - 1;
+y = (2 ** z) - y - 1
 ```
 
 ### Addendum

diff --git a/xyz_vs_tms.md b/xyz_vs_tms.md
@@ -46,4 +46,6 @@ y = (2 ** z) - y - 1;
 
 ### Addendum
 
-When I say 'no difference' or 'no advantage' I mean for most maps. If you have some weird projection, use TMS but ideally don't make a tiled map in a weird projection in the first place. If you're forced to use OSGeo standards, do that but try to find a different job.
+When I say 'no difference' or 'no advantage' I mean for most maps. If you have some weird projection, use TMS but ideally don't make a tiled map in a weird projection in the first place. If you're forced to use OSGeo standards, do that but try to find a different job.
+
+This originally credited OGC with TMS. It was OSGeo. OGC has WMTS. Don't use that either.
diff --git a/xyz_vs_tms.md b/xyz_vs_tms.md
@@ -8,7 +8,7 @@ Good examples are OpenStreetMap, Google Maps, MapBox, MapQuest, etc. Lots of map
 
 Most of those are in XYZ. The best documentation for that is [slippy map tilenames](http://wiki.openstreetmap.org/wiki/slippy_map_tilenames) on the OSM Wiki.
 
-Some of them are in TMS instead. TMS is an OGC spec. [Here's the wiki page on it](http://en.wikipedia.org/wiki/Tile_Map_Service). It's less popular and few services support the whole spec.
+Some of them are in TMS instead. TMS is an OSGeo spec. [Here's the wiki page on it](http://en.wikipedia.org/wiki/Tile_Map_Service). It's less popular and few services support the whole spec.
 
 There are no advantages of XYZ over TMS or vice-versa for most maps*, but XYZ is more popular.
 
@@ -46,4 +46,4 @@ y = (2 ** z) - y - 1;
 
 ### Addendum
 
-When I say 'no difference' or 'no advantage' I mean for most maps. If you have some weird projection, use TMS but ideally don't make a tiled map in a weird projection in the first place. If you're forced to use OGC standards, do that but try to find a different job.
+When I say 'no difference' or 'no advantage' I mean for most maps. If you have some weird projection, use TMS but ideally don't make a tiled map in a weird projection in the first place. If you're forced to use OSGeo standards, do that but try to find a different job.
diff --git a/xyz_vs_tms.md b/xyz_vs_tms.md
@@ -0,0 +1,49 @@
+The difference between XYZ and TMS tiles and how to convert between them
+
+Lots of tile-based maps use either the XYZ or TMS scheme. These are the maps that have tiles
+ending in `/0/0/0.png` or something. Sometimes if it's a script, it'll look like
+`&z=0&y=0&x=0` instead. Anyway, these are usually maps in Spherical Mercator.
+
+Good examples are OpenStreetMap, Google Maps, MapBox, MapQuest, etc. Lots of maps.
+
+Most of those are in XYZ. The best documentation for that is [slippy map tilenames](http://wiki.openstreetmap.org/wiki/slippy_map_tilenames) on the OSM Wiki.
+
+Some of them are in TMS instead. TMS is an OGC spec. [Here's the wiki page on it](http://en.wikipedia.org/wiki/Tile_Map_Service). It's less popular and few services support the whole spec.
+
+There are no advantages of XYZ over TMS or vice-versa for most maps*, but XYZ is more popular.
+
+## Converting
+
+Let's get to the point. The only difference between the two is a flipped y coordinate.
+
+In math:
+
+    y = (2^z) - y - 1;
+
+javascript
+
+```javascript
+y = Math.pow(2, z) - y - 1;
+```
+
+php
+
+```php
+y = pow(2, z) - y - 1;
+```
+
+python
+
+```php
+y = (2 ** z) - y - 1;
+```
+
+ruby
+
+```ruby
+y = (2 ** z) - y - 1;
+```
+
+### Addendum
+
+When I say 'no difference' or 'no advantage' I mean for most maps. If you have some weird projection, use TMS but ideally don't make a tiled map in a weird projection in the first place. If you're forced to use OGC standards, do that but try to find a different job.
No results found