在Geodjango + Postgres中存储一个圈子 [英] Store a Circle in Geodjango + Postgres

问题描述

想要在geodjango字段中存储一个圆圈，所以我可以使用geodjango查询__contains来查找一个点是否在圆圈中（类似于使用PolygonField可以做的）。

Looking to store a circle in a geodjango field so I can use the geodjango query __contains to find out if a point is in the circle (similar to what can be done with a PolygonField).

目前将其存储为十进制半径和GeoDjango点字段，但需要一种查询数据库中某个位置列表的方法，以使这些变化的圆（点域和半径）包含我的搜索点/ lat）。

Currently have it stored as a Decimal radius and GeoDjango Point Field, but need a way to query a list of locations in the DB such that these varying circles (point field and radii) contain my search point (long/lat).

希望是有道理的。

推荐答案

PostGIS支持 CurvePolygon 和 CircularString 几何类型，可用于存储曲面几何。例如，x = 10，y = 10的2单位半径已被64点缓冲多边形近似为：

Technically speaking, PostGIS supports CurvePolygon and CircularString geometry types, which can be used to store curved geometries. For example, a 2-unit radius around x=10, y=10 that has been approximated by a 64-point buffered polygon is:

SELECT ST_AsText(ST_LineToCurve(ST_Buffer(ST_MakePoint(10, 10), 2, 16)));
                   st_astext
------------------------------------------------
 CURVEPOLYGON(CIRCULARSTRING(12 10,8 10,12 10))
(1 row)

但是，这种方法通常不会完成，因为对这种几何类型的支持非常有限（即 ST_AsSVG ，以及别人不行）。这些几何类型可能会导致很多的悲伤，我建议不要这样做。

However, this approach is not typically done, as there is very limited support for this geometry type (i.e., ST_AsSVG, and others won't work). These geometry types will likely cause plenty of grief, and I'd recommend not doing this.

通常，所有几何体都存储为一种良好支持的类型： POINT ， LINESTRING 或 POLYGON （可选 MULTI - prefix）。使用这些类型，请使用 ST_DWithin 函数（例如， GeoDjango 调用此__dwithin，另请参阅此问题）来查询是否另一个几何在一定距离内。例如，如果您有点位置，您可以从点了解其他几何是否在一定距离内（即，半径）。

Typically, all geometries are stored as a well supported type: POINT, LINESTRING or POLYGON (with optional MULTI- prefix). With these types, use the ST_DWithin function (e.g., GeoDjango calls this __dwithin, see also this question) to query if another geometry is within a specified distance. For example, if you have a point location, you can see if other geometries are within a certain distance (i.e., radius) from the point.

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