This topic describes the ST_Value function. This function returns the pixel value of a band.
Syntax
float8 ST_Value(raster raster_obj,
integer band,
integer column_sn,
integer row_sn,
boolean exclude_nodata default true);
float8 ST_Value(raster raster_obj,
integer band,
float8 x,
float8 y,
boolean exclude_nodata default true);
Parameters
Parameter | Description |
---|---|
raster_obj | The raster object that you want to clip. |
band | The number of the band from which you want to obtain the pixel value. The band number starts from 0. |
column_sn | The number of the column in which the pixel is located. The number of the column is calculated from the upper-left corner of the raster object. |
row_sn | The number of the row in which the pixel is located. The number of the row is calculated from the upper-left corner of the raster object. |
x | The x coordinate of the pixel. |
y | The y coordinate of the pixel. |
exclude_nodata | Specifies whether to return a NoData value.
If the value is true and the pixel value is NoData, NULL is returned. |
Description
This function returns the pixel value of a band based on the x and y coordinates as well as the row number or column number of the pixel.
Examples
SELECT ST_VALUE(rast_obj, 0, 10, 20)
FROM raster_table
WHERE id = 1;
---------
169
SELECT ST_Value(rast_obj, 0, 150::float8, 20::float8, false)
from raster_table
WHERE id=3;
----------
77