ECI to Geodetic conversion.

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## [2.0.0]
 
+* ECI to Geodetic conversion.
+
+## [2.0.0]
+
 * Introduce Angle class.
 
 ## [1.0.3]

lib/src/eci.dart

@@ -27,4 +27,44 @@ class EarthCenteredInertial {
   EarthCenteredEarthFixed toEcfByDateTime(DateTime utc) {
     return toEcf(utc.toUtc().gsmt);
   }
+
+  LatLngAlt toGeodetic(Planet planet, double gmst) {
+    // http://www.celestrak.com/columns/v02n03/
+    final a = planet.radius;
+    final f = planet.flattening;
+    final e2 = (2 * f) - (f * f);
+
+    final R = sqrt((x * x) + (y * y));
+
+    var longitude = atan2(y, x) - gmst;
+    while (longitude < -pi) {
+      longitude += pi * 2;
+    }
+    while (longitude > pi) {
+      longitude -= pi * 2;
+    }
+
+    const int kmax = 20;
+    var k = 0;
+    var latitude = atan2(z, sqrt((x * x) + (y * y)));
+    var C = 1.0;
+    while (k < kmax) {
+      C = 1 / sqrt(1 - (e2 * (sin(latitude) * sin(latitude))));
+      latitude = atan2(z + (a * C * e2 * sin(latitude)), R);
+      k += 1;
+    }
+
+    final height = (R / cos(latitude)) - (a * C);
+
+    return LatLngAlt(
+      Angle.radian(latitude),
+      Angle.radian(longitude),
+      height,
+    );
+  }
+
+  LatLngAlt toGeodeticByDateTime(Planet planet, DateTime utc) {
+    final gmst = Julian.fromDateTime(utc).toGmst();
+    return toGeodetic(planet, gmst);
+  }
 }

lib/src/look_angle.dart

@@ -20,6 +20,6 @@ class LookAngle {
 
   @override
   String toString() {
-    return 'Azimuth: ${azimuth.degrees}°, Elevation: ${elevation.degrees}°, Range: ${range}';
+    return 'Azimuth: ${azimuth.degrees}°, Elevation: ${elevation.degrees}°, Range: $range';
   }
 }

pubspec.yaml

@@ -1,6 +1,6 @@
 name: latlng
 description: GeoJSON, Geodesy and Geographical calculations for Dart. Provides LatLong and Mercator projection (EPSG4326).
-version: 2.0.0
+version: 2.0.1
 repository: https://github.com/xclud/dart_latlng
 homepage: https://pwa.ir