RGeo 0.5.2 and RGeo::CoordSys::SRSDatabase::ActiveRecordTabl

Question

首先，如果这真的很简单，我很抱歉，但我似乎无法弄清楚。我正在使用 RGeo 在 UTM 和经度/经度之间进行转换，就像这样;

 srs_database = RGeo::CoordSys::SRSDatabase::ActiveRecordTable.new
 # create the coordinate factory for the relevant UTM zone
 utm_factory = RGeo::Cartesian.factory(:srid => srid,
                                       :srs_database => srs_database)
 utm_location = utm_factory.point(easting, northing)
 # create the standard WGS84 lat/long coordinate factory
 wgs84_proj4 = '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs'
 wgs84_factory = RGeo::Geographic.spherical_factory(proj4: wgs84_proj4, :srid => 4326)
 # perform the UTM -> lat/long cast
 RGeo::Feature.cast(utm_location, :factory => wgs84_factory, :project => true)

如您所见，我正在使用RGeo::CoordSys::SRSDatabase::ActiveRecordTable.

我刚刚升级到RGeo 0.5.2，我注意到这个类已被弃用。

很公平，但我现在不确定替代方法是什么......我已经四处寻找，似乎找不到正确的文档。

此外，我的原始方法对我来说总是有点复杂 - 有没有更简单的方法来完成 UTM - 使用 RGeo>经度/经度转换？

提前感谢！

本

Answer 1

好吧，实际上我很快就解决了这个问题。这是对我有用的：

 if hemisphere == 'S'
   srid = 32700 + number.to_i
   utm_proj4 = "+proj=utm +zone=#{zone} +south +datum=WGS84 +units=m +no_defs"
 else
   srid = 32600 + number.to_i
   utm_proj4 = "+proj=utm +zone=#{zone} +datum=WGS84 +units=m +no_defs"
 end
 # create both the UTM and lat / long factories (we will project between them)
 utm_factory = RGeo::Cartesian.simple_factory(srid: srid, proj4: utm_proj4)
 wgs84_factory = RGeo::Geographic.spherical_factory(srid: 4326, proj4: '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs')
 # create the UTM location
 utm_location = utm_factory.point(easting, northing)
 # perform the UTM -> lat/long cast
 RGeo::Feature.cast(utm_location, :factory => wgs84_factory, :project => true)

我

正在根据我从spatial_ref_sys桌上提取的 Proj4 字符串创建自己的工厂。

我不确定这是否"正确"，可能有更好的方法可以做到这一点。

但我希望这对某人有所帮助！ :)

Answer 2

另一种方法：

EPSG_4326 = RGeo::CoordSys::Proj4.new("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs")
EPSG_3857 = RGeo::CoordSys::Proj4.new("+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")
RGeo::CoordSys::Proj4.transform(EPSG_3857, geom, EPSG_4326, RGeo::Geographic.spherical_factory)

生成具有适当坐标的新RGeo::Geographic::SphericalPointImpl。