Use ST_SetValue to change a pixel value in a raster by geometry or coordinates - ApsaraDB RDS

Sets the pixel value of a raster object at a specified location, identified either by row and column or by a geometry shape.

Syntax

Overload 1: set by row and column

raster ST_SetValue(raster raster_obj,
                   integer row,
                   integer column,
                   double value,
                   integer band);

Overload 2: set by geometry

raster ST_SetValue(raster raster_obj,
                   geometry geom,
                   double value,
                   integer band default 0,
                   boolean rebuild_pyd default true,
                   cstring setvalueOptions default '');

Parameters

Parameter	Type	Description
`raster_obj`	raster	The raster object to update.
`row`	integer	The row number of the pixel to update.
`column`	integer	The column number of the pixel to update.
`value`	double	The new pixel value.
`band`	integer	The band number of the pixel to update.
`geom`	geometry	The geometry that defines the region in which pixel values are updated.
`rebuild_pyd`	boolean	Specifies whether to rebuild the pyramid after updating pixel values.
`setvalueOptions`	cstring	Additional options for the update operation, passed as a JSON string. See the following table for supported fields.

setvalueOptions fields

Field	Type	Default	Description
`window_clip`	bool	false	Specifies whether to use the bounding box of the geometry object as the update region. `true` uses the minimum bounding rectangle (MBR) of the geometry object. `false` uses the geometry object itself.
`rast_coord`	bool	false	Specifies whether the input geometry uses pixel coordinates. `true` means pixel coordinates are used, where the x-coordinate maps to the column number and the y-coordinate maps to the row number, both starting from 0. `false` means pixel coordinates are not used.

Examples

Read the pixel value at row 0, column 2, band 1:

SELECT ST_Value(rast, 0, 2, 1) FROM raster_table ORDER BY id;

Set pixel values to 250.0 at the locations defined by a MULTIPOINT geometry on band 0, with pyramid rebuild enabled:

UPDATE raster_table
SET rast = ST_SetValue(rast, ST_GeomFromText('MULTIPOINT(0 0, 2 2, 10 10)', 4326), 250.0, 0, true);

Set pixel values to 10.0 along a LINESTRING using pixel coordinates (rast_coord: true), without rebuilding the pyramid:

UPDATE raster_table
SET rast = ST_SetValue(rast, ST_GeomFromText('LINESTRING(211 77, 233 100)', 4326), 10.0, 0, false, '{"rast_coord":true}');