geoNear返回的距离不正确 [英] geoNear returns incorrect distance
问题描述
我正在使用Java中的mongodb地理功能，并且遇到以下问题，运行命令'geoNear':
I'm playing with geo features of mongodb in Java and i'm facing to the following problem running command 'geoNear':
给出:
- 一个带有GeoJSON对象的名为"GEOENTITIES"的集合
-
使用Java代码(使用Jongo)对该集合进行索引:
- A collection named 'GEOENTITIES' with GeoJSON objects
This collection is indexed with the Java code (using Jongo):
collection.ensureIndex("{ coordinates : '2dsphere' }");
存在一个坐标为[48.0，9.0]的文档(示例中名为"A")
A document (named 'A' for the example) exists with coordinates equals to [48.0, 9.0]
执行时:
{geoNear: 'GEOENTITIES', near: [48.0,9.1], spherical: true, num: 5, distanceMultiplier: 6371}
然后:
我得到命令结果:
{ "dis" : 11.11949328574724 , "obj" : { "coordinates" : [ 48.0 , 9.0] , "_id" : { "$oid" : "51a62a5485878b1ceca38ab3"} , "name" : "Toto"}}
为什么距离为11.11(公里)，而根据 http://williams.best计算得出的距离.vwh.net/gccalc.htm -例如-是7.46吗?我认为我做错了什么，但看不到，也许经过更多实验的人可以帮忙?
Why the distance is 11.11 (kilometers) whereas the calculated one from http://williams.best.vwh.net/gccalc.htm - for example - is 7.46 ? I think i did something wrong but don't see what, maybe someone more experimented can help?
推荐答案
交换坐标.您需要(纬度，经度):
Swap your coordinates. You need (long, lat):
在MongoDB 2.4中，类地球的默认基准是WGS84.坐标轴顺序是经度，纬度.
The default datum for an earth-like sphere in MongoDB 2.4 is WGS84. Coordinate-axis order is longitude, latitude.
http://docs.mongodb.org/manual/core/2dsphere/
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