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    PolarDB:ST_AddZ

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    PolarDB:ST_AddZ

    Last Updated:Mar 28, 2026

    Assigns a Z coordinate to a geometry based on raster band values.

    Syntax

    geometry ST_AddZ(raster source,
                 geometry geom,
                 integer pyramid,
                 integer band);

    Parameters

    ParameterDescription
    sourceThe source raster.
    geomThe geometry to assign a Z coordinate to.
    pyramidThe pyramid level of the raster. Valid values start from 0. Default value: 0.
    bandThe raster band to read values from. Valid values start from 0. Default value: 0.

    Description

    ST_AddZ reads pixel values from the specified band and pyramid level of a raster, then sets those values as the Z coordinate of the input geometry.

    • If the raster is georeferenced, the function returns a geographic coordinate.

    • If the raster is not georeferenced, the function returns a pixel coordinate.

    Note All points in the geometry must fall within the raster bounds.

    Examples

    Query the Z coordinate from pyramid level 0, band 0:

    SELECT ST_AddZ(rast_object, ST_GeomFromText('POINT(120.5 30.6)', 4326), 0, 0)
FROM raster_table;

    Output:

    POINT Z(120.5 30.6 27)

    Query the Z coordinate from pyramid level 1, band 1:

    SELECT ST_AddZ(rast_object, ST_GeomFromText('POINT(120.5 30.6)', 4326), 1, 1)
FROM raster_table;

    Output:

    POINT Z(120.5 30.6 115)