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RGeo / Rails で Google マップの地理データを処理するDaniel Azuma のソリューションの実装に問題があります。

設定

ロケーション テーブル:

create_table "locations", force: :cascade do |t|
  t.string   "name",        
  t.geometry "polygon", limit: {:srid=>3857, :type=>"polygon"}
end

ロケーション クラス:

class Location < ActiveRecord::Base

  # Create a simple mercator factory. This factory itself is
  # geographic (latitude-longitude) but it also contains a
  # companion projection factory that uses EPSG 3857.
  FACTORY = RGeo::Geographic.simple_mercator_factory

  # To interact in projected coordinates,
  # just use the "polygon" attributes directly.
  def polygon_projected
    self.polygon
  end
  def polygon_projected=(value)
    self.polygon = value
  end

  # To use geographic (lat/lon) coordinates,
  # convert them using the wrapper factory.
  def polygon_geographic
    FACTORY.unproject(self.polygon)
  end
  def polygon_geographic=(value)
    self.polygon = FACTORY.project(value)
  end

  def self.from_geojson(geojson)

    location = Location.new
    decoded_polygon = RGeo::GeoJSON.decode(geojson, json_parser: :json, geo_factory: RGeo::Geographic.simple_mercator_factory)
    location.polygon_geographic = decoded_polygon
    return location

  end

end

初期化子/rgeo.rb:

RGeo::ActiveRecord::SpatialFactoryStore.instance.tap do |config|
  # By default, use the GEOS implementation for spatial columns.
  config.default = RGeo::Geos.factory_generator
end

（ hereおよびhereから派生したソリューション）

問題

それでは、Google マップの座標を含む geojson シェイプから新しい Location オブジェクトを作成します。

manhattan_polygon_data = '{"type":"Polygon","coordinates":[[[-73.9784998975546,40.7367992185915],[-73.9808911983494,40.7334453322506],[-73.9899687850649,40.7350399153528],[-73.9894998975546,40.7395992185915]]]}'
location = Location.from_geojson(manhattan_polygon_data)

この時点で、すべての地理プロパティが適切に機能しています。

# Test geo properties:
location.polygon_projected
=> #<RGeo::Geos::CAPIPolygonImpl:0x3fc428c0c7dc "POLYGON ((-8235248.938246019 4973596.780357394, -8235515.136632829 4973104.057720993, -8236525.648963631 4973338.316345756, -8236473.452644745 4974008.150049943, -8235248.938246019 4973596.780357394))">
location.polygon_geographic
=> #<RGeo::Geographic::ProjectedPolygonImpl:0x3fc425d137a0 "POLYGON ((-73.9784998975546 40.73679921859151, -73.9808911983494 40.73344533225058, -73.9899687850649 40.73503991535281, -73.9894998975546 40.73959921859151, -73.9784998975546 40.73679921859151))">

しかし、データベースを保存して再読み込みすると、何か問題が発生します。

# Save and retrieve from DB:
location.save!
location_from_db = Location.find(location.id)

# Test geo properties again:
location_from_db.polygon_projected
=> #<RGeo::Geos::CAPIPolygonImpl:0x3fc425cfb664 "POLYGON ((-8235248.938246019 4973596.780357394, -8235515.136632829 4973104.057720993, -8236525.648963631 4973338.316345756, -8236473.452644745 4974008.150049943, -8235248.938246019 4973596.780357394))">
location_from_db.polygon_geographic
RGeo::Error::InvalidGeometry: You can unproject only features that are in the projected coordinate space.
    from /usr/local/lib/ruby/gems/2.3.0/gems/rgeo-0.5.3/lib/rgeo/geographic/factory.rb:270:in `unproject'

両方のオブジェクトの投影されたジオメトリが同等であることを考えると、後者のunproject操作が失敗する理由がわかりません。

4

1 に答える 1

2

ここで私の答えを見つけました：Simple Mercator Factory Project/Unproject - Google Groups

問題は、ActiveRecord アダプターで使用されていたものとは異なるファクトリ インスタンスをプロパティに使用していたことです。解決策は、イニシャライザで単純なメルカトル ファクトリの単一のインスタンスを作成することです。

ロケーション クラス:

class Location < ActiveRecord::Base

  # To interact in projected coordinates,
  # just use the "polygon" attributes directly.
  def polygon_projected
    self.polygon
  end
  def polygon_projected=(value)
    self.polygon = value
  end

  # To use geographic (lat/lon) coordinates,
  # convert them using the wrapper factory.
  def polygon_geographic
    FACTORY.unproject(self.polygon)
  end
  def polygon_geographic=(value)
    self.polygon = FACTORY.project(value)
  end

  def self.from_geojson(geojson)

    location = Location.new
    decoded_polygon = RGeo::GeoJSON.decode(geojson, json_parser: :json, geo_factory: RGeo::Geographic.simple_mercator_factory)
    location.polygon_geographic = decoded_polygon
    return location

  end

end

初期化子/rgeo.rb:

# Create a single instance of simple mercator factory. 
# This factory itself is geographic (latitude-longitude) 
# but it also contains a companion projection factory that uses EPSG 3857.
FACTORY = RGeo::Geographic.simple_mercator_factory

RGeo::ActiveRecord::SpatialFactoryStore.instance.tap do |config|
  config.default = FACTORY.projection_factory
end
于 2016-12-25T17:29:30.467 に答える