Create Fishnet Grid
Make a 2D grid of rectangular polygons, which is sometimes called a fishnet grid.
Use the following source for a set returning function:
CREATE OR REPLACE FUNCTION ST_CreateFishnet( nrow integer, ncol integer, xsize float8, ysize float8, x0 float8 DEFAULT 0, y0 float8 DEFAULT 0, OUT "row" integer, OUT col integer, OUT geom geometry) RETURNS SETOF record AS $$ SELECT i + 1 AS row, j + 1 AS col, ST_Translate(cell, j * $3 + $5, i * $4 + $6) AS geom FROM generate_series(0, $1 - 1) AS i, generate_series(0, $2 - 1) AS j, ( SELECT ('POLYGON((0 0, 0 '||$4||', '||$3||' '||$4||', '||$3||' 0,0 0))')::geometry AS cell ) AS foo; $$ LANGUAGE sql IMMUTABLE STRICT;
Where input parameters:
nrow
integer- number of rows in y-direction
ncol
integer- number of columns in x-direction
xsize
float8- cell size length in x-direction
ysize
float8- cell size length in x-direction
x0
float8 (optional)- origin offset in x-direction; DEFAULT is 0
y0
float8 (optional)- origin offset in y-direction; DEFAULT is 0
Returning output parameters are:
row
integer- row number, starting from 1 at the bottom
col
integer- column number, starting from 1 at the left
geom
geometry- grid cell geometry
Example:
SELECT ST_Collect(cells.geom) FROM ST_CreateFishnet(4, 6, 10, 10) AS cells;
Last modified
11 years ago
Last modified on 06/16/13 21:25:18
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