ST_PixelOfValue
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Name

ST_PixelOfValue — 获取其值等于搜索值的像素的Columnx，Rowy坐标。

Synopsis

setof record ST_PixelOfValue ( raster rast , integer nband , double precision[] search , boolean exclude_nodata_value=true ) ;

setof record ST_PixelOfValue ( raster rast , double precision[] search , boolean exclude_nodata_value=true ) ;

setof record ST_PixelOfValue ( raster rast , integer nband , double precision search , boolean exclude_nodata_value=true ) ;

setof record ST_PixelOfValue ( raster rast , double precision search , boolean exclude_nodata_value=true ) ;

描述

获取其值等于搜索值的像素的列x、行坐标。如果未指定波段，则假定为波段1。

可用性：2.1.0

示例 

SELECT
    (pixels).*
FROM (
    SELECT
        ST_PixelOfValue(
            ST_SetValue(
                ST_SetValue(
                    ST_SetValue(
                        ST_SetValue(
                            ST_SetValue(
                                ST_AddBand(
                                    ST_MakeEmptyRaster(5, 5, -2, 2, 1, -1, 0, 0, 0),
                                    '8BUI'::text, 1, 0
                                ),
                                1, 1, 0
                            ),
                            2, 3, 0
                        ),
                        3, 5, 0
                    ),
                    4, 2, 0
                ),
                5, 4, 255
            )
        , 1, ARRAY[1, 255]) AS pixels
) AS foo

 val | x | y
-----+---+---
   1 | 1 | 2
   1 | 1 | 3
   1 | 1 | 4
   1 | 1 | 5
   1 | 2 | 1
   1 | 2 | 2
   1 | 2 | 4
   1 | 2 | 5
   1 | 3 | 1
   1 | 3 | 2
   1 | 3 | 3
   1 | 3 | 4
   1 | 4 | 1
   1 | 4 | 3
   1 | 4 | 4
   1 | 4 | 5
   1 | 5 | 1
   1 | 5 | 2
   1 | 5 | 3
 255 | 5 | 4
   1 | 5 | 5
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