Postgis ST_Distance（最小距离计算）

Question

我有一个多边形类型的几何体，我正在计算一个POINT的最小距离，可能是在多边形几何体的内部（由360个点组成一个封闭的几何体），或者是通过postgis的ST_Distance方法在多边形几何体的外部，当POINT在几何图形外部，但是如果POINT在几何图形内部，则距离为0，无论POINT是在几何图形内部还是几何图形外部，我都希望与最接近多边形几何图形的点的距离最小。

Answer 1

It looks like you want the distance to the polygon shell, or the exterior ring. If you have a POLYGON try finding the distance to ST_ExteriorRing(poly_geom) . For MULTIPOLYGONs, see manual page for ST_ExteriorRing .

Answer 2

If your point is inside the polygon, then its distance from it is zero. It sounds like you want to calculate the distance from the edge of the polygon.

In that case you actually want to create a geometry that is a line, not a polygon, that is the same as the border of the polygon. Then your ST_Distance from your point to that line will be the result you are looking for.