ST_PixelAsCentroids
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名稱

ST_PixelAsCentroids — 傳回柵格波段中每個像素的質心（點幾何），以及每個像素的值、X 和 Y 柵格座標。點幾何是像素所代表區域的質心。

概要

setof record ST_PixelAsCentroids(raster rast, integer band=1, boolean exclude_nodata_value=TRUE);

描述

傳回柵格波段中每個像素的質心（點幾何），以及每個像素的值、X 和 Y 柵格座標。點幾何是像素所代表區域的質心。

回傳記錄格式： geom 幾何, val 雙精度, x 整數, y 整數。

[Note]

當 exclude_nodata_value = TRUE 時，僅會傳回值不是 NODATA 的像素作為點。

增強功能： 3.2.0 現在以 C 實作，速度更快。

變更： 2.1.1 變更 exclude_nodata_value 的行為。

可用性： 2.1.0

範例

 --LATERAL syntax requires PostgreSQL 9.3+
SELECT x, y, val, ST_AsText(geom)
    FROM (SELECT dp.* FROM dummy_rast, LATERAL ST_PixelAsCentroids(rast, 1) AS dp WHERE rid = 2) foo;
 x | y | val |           st_astext
---+---+-----+--------------------------------
 1 | 1 | 253 | POINT(3427927.775 5793243.975)
 2 | 1 | 254 | POINT(3427927.825 5793243.975)
 3 | 1 | 253 | POINT(3427927.875 5793243.975)
 4 | 1 | 254 | POINT(3427927.925 5793243.975)
 5 | 1 | 254 | POINT(3427927.975 5793243.975)
 1 | 2 | 253 | POINT(3427927.775 5793243.925)
 2 | 2 | 254 | POINT(3427927.825 5793243.925)
 3 | 2 | 254 | POINT(3427927.875 5793243.925)
 4 | 2 | 253 | POINT(3427927.925 5793243.925)
 5 | 2 | 249 | POINT(3427927.975 5793243.925)
 1 | 3 | 250 | POINT(3427927.775 5793243.875)
 2 | 3 | 254 | POINT(3427927.825 5793243.875)
 3 | 3 | 254 | POINT(3427927.875 5793243.875)
 4 | 3 | 252 | POINT(3427927.925 5793243.875)
 5 | 3 | 249 | POINT(3427927.975 5793243.875)
 1 | 4 | 251 | POINT(3427927.775 5793243.825)
 2 | 4 | 253 | POINT(3427927.825 5793243.825)
 3 | 4 | 254 | POINT(3427927.875 5793243.825)
 4 | 4 | 254 | POINT(3427927.925 5793243.825)
 5 | 4 | 253 | POINT(3427927.975 5793243.825)
 1 | 5 | 252 | POINT(3427927.775 5793243.775)
 2 | 5 | 250 | POINT(3427927.825 5793243.775)
 3 | 5 | 254 | POINT(3427927.875 5793243.775)
 4 | 5 | 254 | POINT(3427927.925 5793243.775)
 5 | 5 | 254 | POINT(3427927.975 5793243.775)