ST_TPI
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Name

ST_TPI — Returns a raster with the calculated Topographic Position Index.

Synopsis

raster ST_TPI(raster rast, integer nband, raster customextent, text pixeltype="32BF" , boolean interpolate_nodata=FALSE );

Descripción

Calculates the Topographic Position Index, which is defined as the focal mean with radius of one minus the center cell.

[Note]

This function only supports a focalmean radius of one.

Disponibilidad: 2.1.0

Ejemplos

WITH foo AS (
    SELECT ST_SetValues(ST_AddBand(ST_MakeEmptyRaster(5, 5, 0, 0, 1, -1, 0, 0, 0), 1, '32BF', 0, -9999),
        1, 1, 1, ARRAY[
            [1, 1, 2, 3, 3],
            [1, 2, 4, 15, 3],
            [2, 4, 10, 7, 5],
            [3, 5, 7, 6, 4],
            [3, 3, 5, 4, 4]
        ]::double precision[][]
    ) AS rast
)
SELECT ST_Value(ST_TPI(rast, 1, '32BF'), 3, 3) AS tpi
FROM foo;
3.75