ST_PixelAsCentroids-PolarDB(PolarDB)-阿里云帮助中心

Converts pixels at a specified position of a raster into geometry objects, each represented by the centroid of the pixel.

Syntax

setof record ST_PixelAsCentroids(raster raster_obj,
    integer band default  0,
    integer pyramid default 0,
    boolean exclude_nodata_value default true,
    out integer rowsn,
    out integer columnsn,
    out integer bandsn,
    out double value,
    out geometry geom);

Parameters

Parameter	Type	Default	Description
`raster_obj`	raster	—	The raster to query.
`band`	integer	0	The band ID to query. Valid band IDs start from 0.
`pyramid`	integer	0	The pyramid level to query.
`exclude_nodata_value`	boolean	true	Specifies whether to exclude NoData pixels.
`rowsn`	out integer	—	The row number of the pixel.
`columnsn`	out integer	—	The column number of the pixel.
`bandsn`	out integer	—	The band ID of the pixel.
`value`	out double	—	The pixel value.
`geom`	out geometry	—	The spatial extent of the pixel.

Description

ST_PixelAsCentroids returns the same results as ST_PixelAsPoints when the ref_point parameter of ST_PixelAsPoints is set to CENTER.

Examples

WITH tmp AS (
SELECT (ST_PixelAsCentroids(rast, 1)).*
FROM rast_table
WHERE id = 10 )
SELECT rowsn, columnsn, bandsn, value, ST_AsEWKT(geom)  FROM tmp WHERE value > 38.0;

----------------------------------------------------
    100 |      100 |      0 |    43 | SRID=4326;POINT(-89.5 0.5)