Class: Geospatial::Location
- Inherits:
-
Object
- Object
- Geospatial::Location
- Defined in:
- lib/geospatial/location.rb
Overview
This location is specifically relating to a WGS84 coordinate on Earth.
Constant Summary collapse
- WGS84_A =
WGS 84 semi-major axis constant in meters
6378137.0
- WGS84_B =
WGS 84 semi-minor axis constant in meters
6356752.3
- EARTH_RADIUS =
(WGS84_A + WGS84_B) / 2.0
- WGS84_E =
WGS 84 eccentricity
8.1819190842622e-2
- R2D =
Radians to degrees multiplier
(180.0 / Math::PI)
- D2R =
(Math::PI / 180.0)
- MIN_LONGITUDE =
-180 * D2R
- MAX_LONGITUDE =
180 * D2R
- VALID_LONGITUDE =
MIN_LONGITUDE...MAX_LONGITUDE
- MIN_LATITUDE =
-90.0 * D2R
- MAX_LATITUDE =
90 * D2R
- VALID_LATITUDE =
MIN_LATITUDE...MAX_LATITUDE
Instance Attribute Summary collapse
-
#latitude ⇒ Object
readonly
-90 -> 90 (equivalent to y).
-
#longitude ⇒ Object
readonly
-180 -> 180 (equivalent to x).
Class Method Summary collapse
Instance Method Summary collapse
- #bounding_box(distance, radius = EARTH_RADIUS) ⇒ Object
-
#distance_from(other_position) ⇒ Object
calculate distance in metres between us and something else ref: codingandweb.blogspot.co.nz/2012/04/calculating-distance-between-two-points.html.
-
#initialize(longitude, latitude) ⇒ Location
constructor
A new instance of Location.
- #to_a ⇒ Object
-
#to_ecef ⇒ Object
Converts latitude, longitude to ECEF coordinate system.
- #to_s ⇒ Object (also: #inspect)
- #valid? ⇒ Boolean
Constructor Details
#initialize(longitude, latitude) ⇒ Location
Returns a new instance of Location.
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# File 'lib/geospatial/location.rb', line 46 def initialize(longitude, latitude) @latitude = latitude @longitude = longitude end |
Instance Attribute Details
#latitude ⇒ Object (readonly)
-90 -> 90 (equivalent to y)
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# File 'lib/geospatial/location.rb', line 66 def latitude @latitude end |
#longitude ⇒ Object (readonly)
-180 -> 180 (equivalent to x)
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# File 'lib/geospatial/location.rb', line 65 def longitude @longitude end |
Class Method Details
.from_ecef(x, y, z) ⇒ Object
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# File 'lib/geospatial/location.rb', line 117 def self.from_ecef(x, y, z) # Constants (WGS ellipsoid) a = WGS84_A e = WGS84_E b = Math::sqrt((a*a) * (1.0-(e*e))) ep = Math::sqrt(((a*a)-(b*b))/(b*b)) p = Math::sqrt((x*x)+(y*y)) th = Math::atan2(a*z, b*p) lon = Math::atan2(y, x) lat = Math::atan2((z+ep*ep*b*(Math::sin(th) ** 3)), (p-e*e*a*(Math::cos(th)**3))) n = a / Math::sqrt(1.0-e*e*(Math::sin(lat) ** 2)) # alt = p / Math::cos(lat)-n return self.new(lat*R2D, lon*R2D) end |
Instance Method Details
#bounding_box(distance, radius = EARTH_RADIUS) ⇒ Object
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# File 'lib/geospatial/location.rb', line 69 def bounding_box(distance, radius = EARTH_RADIUS) raise ArgumentError.new("Invalid distance or radius") if distance < 0 or radius < 0 # angular distance in radians on a great circle angular_distance = distance / radius min_latitude = (self.latitude * D2R) - angular_distance max_latitude = (self.latitude * D2R) + angular_distance if min_latitude > MIN_LATITUDE and max_latitude < MAX_LATITUDE longitude_delta = Math::asin(Math::sin(angular_distance) / Math::cos(self.latitude * D2R)) min_longitude = (self.longitude * D2R) - longitude_delta min_longitude += 2.0 * Math::PI if (min_longitude < MIN_LONGITUDE) max_longitude = (self.longitude * D2R) + longitude_delta; max_longitude -= 2.0 * Math::PI if (max_longitude > MAX_LONGITUDE) else # a pole is within the distance min_latitude = [min_latitude, MIN_LATITUDE].max max_latitude = [max_latitude, MAX_LATITUDE].min min_longitude = MIN_LONGITUDE max_longitude = MAX_LONGITUDE end return { :latitude => Range.new(min_latitude * R2D, max_latitude * R2D), :longitude => Range.new(min_longitude * R2D, max_longitude * R2D), } end |
#distance_from(other_position) ⇒ Object
calculate distance in metres between us and something else ref: codingandweb.blogspot.co.nz/2012/04/calculating-distance-between-two-points.html
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# File 'lib/geospatial/location.rb', line 139 def distance_from(other_position) rlong1 = self.longitude * D2R rlat1 = self.latitude * D2R rlong2 = other_position.longitude * D2R rlat2 = other_position.latitude * D2R dlon = rlong1 - rlong2 dlat = rlat1 - rlat2 a = Math::sin(dlat/2) ** 2 + Math::cos(rlat1) * Math::cos(rlat2) * Math::sin(dlon/2) ** 2 c = 2 * Math::atan2(Math::sqrt(a), Math::sqrt(1-a)) d = EARTH_RADIUS * c return d end |
#to_a ⇒ Object
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# File 'lib/geospatial/location.rb', line 55 def to_a [@longitude, @latitude] end |
#to_ecef ⇒ Object
Converts latitude, longitude to ECEF coordinate system
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# File 'lib/geospatial/location.rb', line 102 def to_ecef clon = Math::cos(lon * D2R) slon = Math::sin(lon * D2R) clat = Math::cos(lat * D2R) slat = Math::sin(lat * D2R) n = WGS84_A / Math::sqrt(1.0 - WGS84_E * WGS84_E * slat * slat) x = n * clat * clon y = n * clat * slon z = n * (1.0 - WGS84_E * WGS84_E) * slat return x, y, z end |
#to_s ⇒ Object Also known as: inspect
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# File 'lib/geospatial/location.rb', line 59 def to_s "#<Location longitude=#{@longitude.to_f} latitude=#{@latitude}>" end |
#valid? ⇒ Boolean
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# File 'lib/geospatial/location.rb', line 51 def valid? VALID_LONGITUDE.include?(longitude) and VALID_LATITUDE.include?(latitude) end |