ST_Contour — Generates a set of vector contours from the provided raster band, using the GDAL contouring algorithm.
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);
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
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;