Name

ST_PixelHeight — 返回以空间参考系的几何单位表示的像素高度。

Synopsis

double precision ST_PixelHeight(raster rast);

描述

返回以空间参考系的几何单位表示的像素高度。在没有倾斜的常见情况下,像素高度只是几何坐标和栅格像素之间的比例。

请参阅 ST_PixelWidth 对于这种关系的图解可视化。

示例:无倾斜的栅格

SELECT ST_Height(rast) As rastheight, ST_PixelHeight(rast) As pixheight,
 ST_ScaleX(rast) As scalex, ST_ScaleY(rast) As scaley, ST_SkewX(rast) As skewx,
        ST_SkewY(rast) As skewy
FROM dummy_rast;

 rastheight | pixheight | scalex | scaley | skewx | skewy
------------+-----------+--------+--------+-------+----------
         20 |         3 |      2 |      3 |     0 |        0
          5 |      0.05 |   0.05 |  -0.05 |     0 |        0
            

示例:倾斜不等于0的栅格

SELECT ST_Height(rast) As rastheight, ST_PixelHeight(rast) As pixheight,
 ST_ScaleX(rast) As scalex, ST_ScaleY(rast) As scaley, ST_SkewX(rast) As skewx,
        ST_SkewY(rast) As skewy
FROM (SELECT ST_SetSKew(rast,0.5,0.5) As rast
        FROM dummy_rast) As skewed;

rastheight |     pixheight     | scalex | scaley | skewx | skewy
-----------+-------------------+--------+--------+-------+----------
        20 |  3.04138126514911 |      2 |      3 |   0.5 |      0.5
         5 | 0.502493781056044 |   0.05 |  -0.05 |   0.5 |      0.5
            

另请参阅

ST_PixelWidth, ST_ScaleX, ST_ScaleY, ST_SkewX, ST_SkewY