ST_STRAIGHTSKELETON

📄字数 894

👁️阅读量 加载中...

功能描述

从几何体计算直骨架。

语法格式

GEOMETRY ST_STRAIGHTSKELETON(GEOMETRY geom);

参数说明

geom：目标GEOMETRY对象。

函数返回类型

GEOMETRY类型

使用说明

• 该函数需要SFCGAL库支持。
• 该函数支持3D对象，并且不会删除Z坐标。
• 该函数支持多面体表面（POLYHEDRALSURFACE）、三角形（TRIANGLE）、不规则三角形格网（Triangulated Irregular Network，TIN）类型几何对象。

示例

SQL> SELECT TO_CHAR(ST_AsText(ST_StraightSkeleton(ST_GeomFromText('POLYGON (( 190 190, 10 190, 10 10, 190 10, 190 20, 160 30, 60 30, 60 130, 190 140, 190 190 ))'))));

+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|                                                                                                                                                                                                                                                                                                                  EXPR1                                                                                                                                                                                                                                                                                                                   |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| MULTILINESTRING((190 190,164.03987973986756 164.03987973986756),(10 190,40.697077206292434 159.30292279370755),(10 10,35 35),(190 10,184.18861169915812 15.811388300841896),(190 20,184.18861169915812 15.811388300841896),(160 30,158.3772233983162 20),(60 30,50 20),(60 130,35 153.15077848154866),(190 140,164.03987973986756 164.03987973986756),(184.18861169915812 15.811388300841896,158.3772233983162 20),(50 20,158.3772233983162 20),(50 20,35 35),(35 153.15077848154866,35 35),(35 153.15077848154866,40.697077206292434 159.30292279370755),(164.03987973986756 164.03987973986756,40.697077206292434 159.30292279370755)) |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

渲染效果如图1和图2所示。

图1 原始多边形

图2 多边形的直骨架