描述

返回限定栅格波段的每个像素的多边形几何图形以及每个像素的值(双精度)、X和Y栅格坐标(整数)。

Return record format: geom 几何体 , val double precision, x integer, y integers.

	什么时候 exclude_nodata_value =TRUE，则只返回其值不是NODATA的那些像素作为点。

	ST_PixelAsPolygons为每个像素返回一个多边形几何体。这与ST_DumpAsPolygons不同，在ST_DumpAsPolygons中，每个几何体表示一个或多个具有相同像素值的像素。

可用性：2.0.0

增强：2.1.0添加了可选参数EXCLUDE_NODATA_VALUE。

已更改：2.1.1更改了EXCLUDE_NODATA_VALUE的行为。

示例

-- get raster pixel polygon
SELECT (gv).x, (gv).y, (gv).val, ST_AsText((gv).geom) geom
FROM (SELECT ST_PixelAsPolygons(
                 ST_SetValue(ST_SetValue(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 0.001, -0.001, 0.001, 0.001, 4269),
                                                    '8BUI'::text, 1, 0),
                                         2, 2, 10),
                             1, 1, NULL)
) gv
) foo;

 x | y | val |                geom
---+---+-----------------------------------------------------------------------------
 1 | 1 |     | POLYGON((0 0,0.001 0.001,0.002 0,0.001 -0.001,0 0))
 1 | 2 |   1 | POLYGON((0.001 -0.001,0.002 0,0.003 -0.001,0.002 -0.002,0.001 -0.001))
 2 | 1 |   1 | POLYGON((0.001 0.001,0.002 0.002,0.003 0.001,0.002 0,0.001 0.001))
 2 | 2 |  10 | POLYGON((0.002 0,0.003 0.001,0.004 0,0.003 -0.001,0.002 0))
  

另请参阅

ST_DumpAsPolygons, ST_PixelAsPolygon, ST_PixelAsPoint, ST_PixelAsPoints, ST_PixelAsCentroid, ST_PixelAsCentroids, ST_AsText