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[英]SQL Geography Datatype , checking Point in Polygon , STIntersects producing wrong result
[英]Checking if a Point is inside a Polygon not working
使用SQL Server 2012,以下查询不断告诉我,当我知道要查找的点不在所使用的多边形内时。 在QGIS 2.2.0中使用相同的数据,我清楚地看到该点在多边形内部(屏幕截图)。
DECLARE @polygon GEOGRAPHY = GEOGRAPHY::STPolyFromText('POLYGON ((-111.0498046875 33.966142265597391, -110.9124755859375 33.472690192666633, -110.94268798828125 32.983324091837417, -111.7364501953125 32.680996432581921, -112.587890625 32.731840896865656, -113.0657958984375 33.307577130152978, -112.9010009765625 33.811102288647007, -112.32147216796875 34.1890858311723, -111.4453125 34.129994745824717, -111.0498046875 33.966142265597391))', 4326);
DECLARE @point GEOGRAPHY = GEOGRAPHY::STPointFromText('POINT (-112.0685317 33.4491407)', 4326);
SELECT @point.STIsValid() AS [PointIsValid], --True
@polygon.STIsValid() AS [PolygonIsValid], --True
@point.STWithin(@polygon) AS [PointWithinPolygon], --False
@point.STIntersects(@polygon) AS [PointIntersectsPolygon], --False
@polygon.STContains(@point) AS [PolygonContainsPoint]; --False
我需要做些什么使查询告诉我点在多边形中? 我已经看到一些搜索结果谈论“方向”,但是我不知道如何指定它。 坐标是从Google Maps JavaScript API捕获的,并使用Entity Framework 6.1保留到数据库中。
我认为您遇到环取向问题 。 您需要颠倒多边形的顺序:
using Microsoft.SqlServer.Types;
using System;
using System.Collections.Generic;
using System.Data.Spatial;
using System.Data.SqlTypes;
namespace SomeNamespace
{
public static class DbGeographyHelper
{
// 4326 is most common coordinate system used by GPS/Maps
// 4326 format puts LONGITUDE first then LATITUDE
private static int _coordinateSystem = 4326;
public static DbGeography CreatePolygon(string wktString)
{
// create polygon is same order as wktString
var sqlGeography = SqlGeography
.STGeomFromText(new SqlChars(wktString), _coordinateSystem)
.MakeValid();
// create the polygon in the reverse order
var invertedSqlGeography = sqlGeography.ReorientObject();
// which ever one is big is probably not the one you want
if (sqlGeography.STArea() > invertedSqlGeography.STArea())
{
sqlGeography = invertedSqlGeography;
}
return DbSpatialServices.Default.GeographyFromProviderValue(sqlGeography);
}
}
}
@Erik的答案是正确的,因为SQL Server排除了我在多边形中指定的区域。 反转多边形可解决此问题。 他的代码是正确的,但是我必须进行修改以适合我的用法,因此这是我在乎的代码:
public static class DbGeographyExtensions {
public static DbGeography PolygonFromGoogleMapsText(
string wellKnownText,
int coordinateSystemId) {
SqlGeography geography = SqlGeography.STGeomFromText(new SqlChars(wellKnownText), coordinateSystemId).MakeValid();
SqlGeography invertedGeography = geography.ReorientObject();
if (geography.STArea() > invertedGeography.STArea()) {
geography = invertedGeography;
}
return DbGeography.FromText(geography.ToString(), coordinateSystemId);
}
}
尝试从@Erik的代码返回时遇到异常,因此我在此处使用了答案中的代码: 实体框架:SqlGeography vs DbGeography
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