PostGIS
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;