説明

NODATA値を除いたラスタの凸包ジオメトリを返します。nbandがNULLの場合には、ラスタの全てのバンドが考慮されます。

Availability: 2.1.0

例

WITH foo AS (
        SELECT
                ST_SetValues(
                        ST_SetValues(
                                ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(9, 9, 0, 0, 1, -1, 0, 0, 0), 1, '8BUI', 0, 0), 2, '8BUI', 1, 0),
                                1, 1, 1,
                                ARRAY[
                                        [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                        [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                        [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                        [0, 0, 0, 1, 0, 0, 0, 0, 1],
                                        [0, 0, 0, 1, 1, 0, 0, 0, 0],
                                        [0, 0, 0, 1, 0, 0, 0, 0, 0],
                                        [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                        [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                        [0, 0, 0, 0, 0, 0, 0, 0, 0]
                                ]::double precision[][]
                        ),
                        2, 1, 1,
                        ARRAY[
                                [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                [1, 0, 0, 0, 0, 1, 0, 0, 0],
                                [0, 0, 0, 0, 1, 1, 0, 0, 0],
                                [0, 0, 0, 0, 0, 1, 0, 0, 0],
                                [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                [0, 0, 0, 0, 0, 0, 0, 0, 0],
                                [0, 0, 1, 0, 0, 0, 0, 0, 0]
                        ]::double precision[][]
                ) AS rast
)
SELECT
        ST_AsText(ST_ConvexHull(rast)) AS hull,
        ST_AsText(ST_MinConvexHull(rast)) AS mhull,
        ST_AsText(ST_MinConvexHull(rast, 1)) AS mhull_1,
        ST_AsText(ST_MinConvexHull(rast, 2)) AS mhull_2
FROM foo

               hull               |                mhull                |               mhull_1               |               mhull_2
----------------------------------+-------------------------------------+-------------------------------------+-------------------------------------
 POLYGON((0 0,9 0,9 -9,0 -9,0 0)) | POLYGON((0 -3,9 -3,9 -9,0 -9,0 -3)) | POLYGON((3 -3,9 -3,9 -6,3 -6,3 -3)) | POLYGON((0 -3,6 -3,6 -9,0 -9,0 -3))
                                        

関連情報

ST_Envelope, ST_ConvexHull, ST_ConvexHull, ST_AsText