Move doc from wiki to repo, closes #85

2015-07-01 07:01:50 -07:00
parent ac8203eec4
commit 509944ea6d
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+Fill given extent with a rectangular coverage
+
+#### Using the function
+
+Create a rectangular grid from a polygon geometry. For example, take the geometry
+
+```sql
+  ST_SetSRID(
+    ST_Envelope(
+      ST_Collect(
+        ST_MakePoint(10000000,-10000000),
+        ST_MakePoint(-10000000,10000000)
+      )
+     ),
+     3857)
+```
+
+We can create a grid as follows, 
+
+```sql
+SELECT CDB_RectangleGrid(
+  ST_SetSRID(
+    ST_Envelope(
+      ST_Collect(
+        ST_MakePoint(10000000,-10000000),
+        ST_MakePoint(-10000000,10000000)
+      )
+     ),
+     3857),
+   1000000,
+   1000000
+) the_geom_webmercator
+```
+
+Which will look something like this,
+
+![rect grid](http://i.imgur.com/HuhOJRs.png)
+
+#### Arguements
+
+CDB_RectangleGrid(ext, width, height, origin)
+
+* **ext** geometry. Extent to fill. Only rectangles with center point falling inside the extent (or at the lower or leftmost edge) will be emitted. The returned hexagons will have the same SRID as this extent.
+* **width** float. Width of each rectangle. Measure is in the same projection as **ext**
+* **height** float. Height of each rectangle. Measure is in the same projection as **ext**
+* **origin** OPTIONAL geometry. Optional origin to allow for exact tiling. If omitted the origin will be 0,0. The parameter is checked for having the same SRID as the extent.