ST_Contour
Name
ST_Contour — Generates a set of vector contours from the provided raster band, using the GDAL contouring algorithm .
Synopsis
setof record
ST_Contour
(
raster
rast
, integer
bandnumber=1
, double precision
level_interval=100.0
, double precision
level_base=0.0
, double precision[]
fixed_levels=ARRAY[]
, boolean
polygonize=false
)
;
Description
Generates a set of vector contours from the provided raster band, using the GDAL contouring algorithm .
When the
fixed_levels
parameter is a non-empty
array, the
level_interval
and
level_base
parameters are ignored.
Input parameters are:
-
rast -
The raster to generate the contour of
-
bandnumber -
The band to generate the contour of
-
level_interval -
The elevation interval between contours generated
-
level_base -
The "base" relative to which contour intervals are applied, this is normally zero, but could be different. To generate 10m contours at 5, 15, 25, ... the LEVEL_BASE would be 5.
-
fixed_levels -
The elevation interval between contours generated
-
polygonize -
If
true, contour polygons will be created, rather than polygon lines.
Return values are a set of records with the following attributes:
-
geom -
The geometry of the contour line.
-
id -
A unique identifier given to the contour line by GDAL.
-
value -
The raster value the line represents. For an elevation DEM input, this would be the elevation of the output contour.
Availability: 3.2.0
Example
WITH c AS ( SELECT (ST_Contour(rast, 1, fixed_levels => ARRAY[100.0, 200.0, 300.0])).* FROM dem_grid WHERE rid = 1 ) SELECT st_astext(geom), id, value FROM c;