Name
ST_PixelAsPolygons — 返回限定栅格带的每个像素的多边形几何图形，以及每个像素的值、X和Y栅格坐标。
Synopsis
setof record
ST_PixelAsPolygons
(
raster
rast
, integer
band=1
, boolean
exclude_nodata_value=TRUE
)
;
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.
![[Note]](images/note.png)
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什么时候
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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))