fix: 🐛 fix degrees vs radians issues

examples/sensor.ts

@@ -1,5 +1,7 @@
 /* eslint-disable no-console */
 import { Satellite } from '@src/objects/Satellite';
+import { calcGmst, ecf2eci, eci2lla, eci2rae } from '@src/transforms/transforms';
+import { DEG2RAD } from '@src/utils/constants';
 import { Sensor } from '../src/objects';
 import { Degrees, Kilometers, SpaceObjectType, TleLine1, TleLine2, Transforms } from '../src/ootk';
 
@@ -30,15 +32,28 @@ const sat = new Satellite({
 
 const date = new Date('2023-12-31T20:51:19.934Z');
 
-const rae = Transforms.ecf2rae(testSensor, {
+const ecf = {
   x: 4000 as Kilometers,
   y: 7000 as Kilometers,
   z: 3000 as Kilometers,
-});
+};
+// const ecf2 = { x: 982.8336640053099, y: -6779.137352354403, z: 3813.7284924837254 } as EcfVec3<Kilometers>;
+
+const rae = Transforms.ecf2rae(testSensor, ecf);
+
+const { gmst } = calcGmst(date);
+const rae2 = eci2rae(date, ecf2eci(ecf, gmst), testSensor);
+const lla = eci2lla(ecf2eci(ecf, gmst), gmst);
 
 console.log(rae);
+console.log(rae2);
+console.log({
+  lat: lla.lat * DEG2RAD,
+  lon: lla.lon * DEG2RAD,
+  alt: lla.alt,
+});
 
 // sat.propagateTo(date);
 
-// console.log(sat.raeOpt(capeCodRadar, date));
-console.log(sat.getJ2000().inertial);
+console.log(sat.raeOpt(testSensor, date));
+console.log(sat.getJ2000(date).toITRF().toGeodetic());

src/objects/Satellite.ts

@@ -265,7 +265,13 @@ export class Satellite {
     const eci = this.getEci(date).position;
     const ecf = Transforms.eci2ecf(eci, gmst);
 
-    return Transforms.ecf2rae(sensor, ecf);
+    const lla = {
+      lat: (sensor.lat * DEG2RAD) as Radians,
+      lon: (sensor.lon * DEG2RAD) as Radians,
+      alt: sensor.alt,
+    };
+
+    return Transforms.ecf2rae(lla, ecf);
   }
 
   /**

src/transforms/transforms.ts

@@ -23,12 +23,14 @@
  * Orbital Object ToolKit. If not, see <http://www.gnu.org/licenses/>.
  */
 
+import { Sensor, Sgp4, Utils } from '@src/ootk';
 import {
   Degrees,
   EcefVec3,
   EcfVec3,
   EciVec3,
   EnuVec3,
+  GreenwichMeanSiderealTime,
   Kilometers,
   LlaVec3,
   RadarSensor,
@@ -38,7 +40,7 @@ import {
   RuvVec3,
   SezVec3,
 } from '../types/types';
-import { DEG2RAD, PI, RAD2DEG, TAU } from '../utils/constants';
+import { DAY_TO_MS, DEG2RAD, PI, RAD2DEG, TAU } from '../utils/constants';
 
 /**
  * Converts Azimuth and Elevation to U and V.
@@ -182,10 +184,35 @@ export function enu2rf<D extends number, A extends number = Radians>({ x, y, z }
   };
 }
 
+/**
+ * Calculates Geodetic Lat Lon Alt to ECF coordinates.
+ */
+export function lla2ecf<D extends number>(lla: LlaVec3<Radians, D>): EcfVec3<D> {
+  const { lon, lat, alt } = lla;
+
+  const a = 6378.137;
+  const b = 6356.7523142;
+  const f = (a - b) / a;
+  const e2 = 2 * f - f * f;
+  const normal = a / Math.sqrt(1 - e2 * (Math.sin(lat) * Math.sin(lat)));
+
+  const x = (normal + alt) * Math.cos(lat) * Math.cos(lon);
+  const y = (normal + alt) * Math.cos(lat) * Math.sin(lon);
+  const z = (normal * (1 - e2) + alt) * Math.sin(lat);
+
+  return {
+    x: <D>x,
+    y: <D>y,
+    z: <D>z,
+  };
+}
+
 /**
  * Calculates Geodetic Lat Lon Alt to ECEF coordinates.
+ *
+ * @deprecated This needs to be validated.
  */
-export function lla2ecf<D extends number>(lla: LlaVec3<Radians, D>): EcefVec3<D> {
+export function lla2ecef<D extends number>(lla: LlaVec3<Degrees, D>): EcefVec3<D> {
   const { lat, lon, alt } = lla;
   const a = 6378.137; // semi-major axis length in meters according to the WGS84
   const b = 6356.752314245; // semi-minor axis length in meters according to the WGS84
@@ -202,13 +229,13 @@ export function lla2ecf<D extends number>(lla: LlaVec3<Radians, D>): EcefVec3<D>
  * Converts LLA to SEZ coordinates.
  * @see http://www.celestrak.com/columns/v02n02/
  */
-export function lla2sez<D extends number>(lla: LlaVec3<Degrees, D>, ecf: EcfVec3<D>): SezVec3<D> {
-  const lat = (lla.lat * DEG2RAD) as Radians;
-  const lon = (lla.lon * DEG2RAD) as Radians;
+export function lla2sez<D extends number>(lla: LlaVec3<Radians, D>, ecf: EcfVec3<D>): SezVec3<D> {
+  const lat = lla.lat;
+  const lon = lla.lon;
 
   const observerEcf = lla2ecf({
-    lat: (lla.lat * DEG2RAD) as Radians,
-    lon: (lla.lon * DEG2RAD) as Radians,
+    lat,
+    lon,
     alt: <Kilometers>0,
   });
 
@@ -375,13 +402,57 @@ export function uv2azel(u: Radians, v: Radians, coneHalfAngle: Radians): { az: R
  * @param ecf The Earth-Centered Fixed (ECF) coordinates.
  * @returns The Right Ascension (RA), Elevation (E), and Azimuth (A) coordinates.
  */
-export function ecf2rae<D extends number>(lla: LlaVec3<Degrees, D>, ecf: EcfVec3<D>): RaeVec3<D, Degrees> {
+export function ecf2rae<D extends number>(lla: LlaVec3<Radians, D>, ecf: EcfVec3<D>): RaeVec3<D, Degrees> {
   const sezCoords = lla2sez(lla, ecf);
   const rae = sez2rae(sezCoords);
 
-  return {
-    rng: rae.rng,
-    az: (rae.az * RAD2DEG) as Degrees,
-    el: (rae.el * RAD2DEG) as Degrees,
+  return { rng: rae.rng, az: (rae.az * RAD2DEG) as Degrees, el: (rae.el * RAD2DEG) as Degrees };
+}
+
+/**
+ * Calculates the Greenwich Mean Sidereal Time (GMST) for a given date.
+ *
+ * @param date - The date for which to calculate the GMST.
+ * @returns An object containing the GMST value and the Julian date.
+ */
+export function calcGmst(date: Date): { gmst: GreenwichMeanSiderealTime; j: number } {
+  const j =
+    Utils.jday(
+      date.getUTCFullYear(),
+      date.getUTCMonth() + 1,
+      date.getUTCDate(),
+      date.getUTCHours(),
+      date.getUTCMinutes(),
+      date.getUTCSeconds(),
+    ) +
+    date.getUTCMilliseconds() * DAY_TO_MS;
+
+  const gmst = Sgp4.gstime(j);
+
+  return { gmst, j };
+}
+
+/**
+ * Converts ECI coordinates to RAE (Right Ascension, Azimuth, Elevation) coordinates.
+ * @param {Date} now - Current date and time.
+ * @param {EciArr3} eci - ECI coordinates of the satellite.
+ * @param {SensorObject} sensor - Sensor object containing observer's geodetic coordinates.
+ * @returns {Object} Object containing azimuth, elevation and range in degrees and kilometers respectively.
+ */
+export function eci2rae(
+  now: Date,
+  eci: EciVec3<Kilometers>,
+  sensor: Sensor,
+): { az: Degrees; el: Degrees; rng: Kilometers } {
+  now = new Date(now);
+  const { gmst } = calcGmst(now);
+
+  const positionEcf = eci2ecf(eci, gmst);
+  const lla = {
+    lat: (sensor.lat * DEG2RAD) as Radians,
+    lon: (sensor.lon * DEG2RAD) as Radians,
+    alt: sensor.alt,
   };
+
+  return ecf2rae(lla, positionEcf);
 }

test/objects/__snapshots__/star.test.ts.snap

@@ -6,8 +6,8 @@ exports[`Basic Star functionality should be able to get ECI coordinates 2`] = `5
 
 exports[`Basic Star functionality should be able to get ECI coordinates 3`] = `-2.4943615850552645e-11`;
 
-exports[`Basic Star functionality should be able to get rae coordinates 1`] = `4.71238898038469`;
+exports[`Basic Star functionality should be able to get rae coordinates 1`] = `270`;
 
-exports[`Basic Star functionality should be able to get rae coordinates 2`] = `0.9966158375158686`;
+exports[`Basic Star functionality should be able to get rae coordinates 2`] = `57.10188128555508`;
 
 exports[`Basic Star functionality should be able to get rae coordinates 3`] = `250000`;

test/objects/star.test.ts

@@ -17,8 +17,8 @@ describe('Basic Star functionality', () => {
   it('should be able to get rae coordinates', () => {
     const rae = star.getRae(
       {
-        lat: <Radians>0,
-        lon: <Radians>0,
+        lat: <Degrees>0,
+        lon: <Degrees>0,
         alt: <Kilometers>0,
       },
       new Date(1661400000000),

test/sat/__snapshots__/sensor.test.ts.snap

@@ -1,121 +1,121 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`Basic Sensor functionality should be able to get rae coordinates 1`] = `2.629108354091844`;
+exports[`Basic Sensor functionality should be able to get rae coordinates 1`] = `2.62910835409574`;
 
-exports[`Basic Sensor functionality should be able to get rae coordinates 2`] = `-0.4265038258082757`;
+exports[`Basic Sensor functionality should be able to get rae coordinates 2`] = `-0.42650382580852597`;
 
-exports[`Basic Sensor functionality should be able to get rae coordinates 3`] = `6156.556070063796`;
+exports[`Basic Sensor functionality should be able to get rae coordinates 3`] = `6156.5560701071345`;
 
-exports[`Basic Sensor functionality should be able to get rae coordinates 4`] = `2.629108354091844`;
+exports[`Basic Sensor functionality should be able to get rae coordinates 4`] = `2.62910835409574`;
 
-exports[`Basic Sensor functionality should be able to get rae coordinates 5`] = `-0.4265038258082757`;
+exports[`Basic Sensor functionality should be able to get rae coordinates 5`] = `-0.42650382580852597`;
 
-exports[`Basic Sensor functionality should be able to get rae coordinates 6`] = `6156.556070063796`;
+exports[`Basic Sensor functionality should be able to get rae coordinates 6`] = `6156.5560701071345`;
 
 exports[`Basic Sensor functionality should create a lookangles array 1`] = `
 Array [
   Object {
-    "az": 180.13876758624156,
-    "el": 0.015361507052862225,
-    "rng": 2342.737908604558,
+    "az": 3.144014604864707,
+    "el": 0.0002681088678837023,
+    "rng": 2342.737908649094,
     "time": 2022-08-25T07:15:53.000Z,
     "type": 0,
   },
   Object {
-    "az": 75.7980806492444,
-    "el": -0.028830957334440976,
-    "maxElPass": 0.17148507081196085,
-    "rng": 2358.7204661051765,
+    "az": 1.3229260740398223,
+    "el": -0.0005031951401863713,
+    "maxElPass": 0.17148507079617165,
+    "rng": 2358.7204660942584,
     "time": 2022-08-25T07:24:24.000Z,
     "type": 2,
   },
   Object {
-    "az": 232.18906583186794,
-    "el": 0.009600433988362477,
-    "rng": 2347.461425625144,
+    "az": 4.052463685880971,
+    "el": 0.0001675591744800231,
+    "rng": 2347.461425652447,
     "time": 2022-08-25T08:50:55.000Z,
     "type": 0,
   },
   Object {
-    "az": 54.52261565864341,
-    "el": -0.02413294135461665,
-    "maxElPass": 1.5418848225221131,
-    "rng": 2359.154162131899,
+    "az": 0.9515991600581195,
+    "el": -0.00042119929302788286,
+    "maxElPass": 1.5418848224515804,
+    "rng": 2359.154162106056,
     "time": 2022-08-25T09:01:48.000Z,
     "type": 2,
   },
   Object {
-    "az": 273.62009396619993,
-    "el": 0.04473721840290453,
-    "rng": 2349.43400753881,
+    "az": 4.775571539307538,
+    "el": 0.0007808117510869499,
+    "rng": 2349.4340075359833,
     "time": 2022-08-25T10:28:25.000Z,
     "type": 0,
   },
   Object {
-    "az": 49.638932677761765,
-    "el": -0.030434434506850978,
-    "maxElPass": 0.3482094176129491,
-    "rng": 2358.137482792154,
+    "az": 0.8663628124171412,
+    "el": -0.0005311810963317111,
+    "maxElPass": 0.34820941760929697,
+    "rng": 2358.137482763319,
     "time": 2022-08-25T10:38:29.000Z,
     "type": 2,
   },
   Object {
-    "az": 302.060157955515,
-    "el": 0.021825330760619138,
-    "rng": 2354.1913017184143,
+    "az": 5.2719442954018465,
+    "el": 0.00038092387390169485,
+    "rng": 2354.1913016947638,
     "time": 2022-08-25T12:06:27.000Z,
     "type": 0,
   },
   Object {
-    "az": 62.062147356797546,
-    "el": -0.047720598190494616,
-    "maxElPass": 0.23309471413013108,
-    "rng": 2355.3145751792804,
+    "az": 1.0831888122507203,
+    "el": -0.0008328815676606213,
+    "maxElPass": 0.2330947141235898,
+    "rng": 2355.3145751584284,
     "time": 2022-08-25T12:15:50.000Z,
     "type": 2,
   },
   Object {
-    "az": 310.644650630328,
-    "el": 0.034319691788985335,
-    "rng": 2351.3514012828773,
+    "az": 5.421771957192329,
+    "el": 0.0005989916117731009,
+    "rng": 2351.3514012538535,
     "time": 2022-08-25T13:43:37.000Z,
     "type": 0,
   },
   Object {
-    "az": 93.78468715091233,
-    "el": -0.05092447343831976,
-    "maxElPass": 0.41989657303646716,
-    "rng": 2346.7733683863107,
+    "az": 1.6368515787551787,
+    "el": -0.0008887997395797053,
+    "maxElPass": 0.41989657303552286,
+    "rng": 2346.773368389268,
     "time": 2022-08-25T13:53:54.000Z,
     "type": 2,
   },
   Object {
-    "az": 302.82920181425385,
-    "el": 0.008831974766942259,
-    "rng": 2350.585020694925,
+    "az": 5.285366642829193,
+    "el": 0.00015414703091340442,
+    "rng": 2350.585020670774,
     "time": 2022-08-25T15:20:18.000Z,
     "type": 0,
   },
   Object {
-    "az": 136.91615645014073,
-    "el": -0.06079535528704331,
-    "maxElPass": 0.9909446544534085,
-    "rng": 2338.0820302051443,
+    "az": 2.3896377292436397,
+    "el": -0.0010610791279322895,
+    "maxElPass": 0.9909446543741702,
+    "rng": 2338.082030237695,
     "time": 2022-08-25T15:31:03.000Z,
     "type": 2,
   },
   Object {
-    "az": 275.6078287616163,
-    "el": 0.009865997778276727,
-    "rng": 2342.5887956584797,
+    "az": 4.810264056144007,
+    "el": 0.00017219413697323465,
+    "rng": 2342.5887956541233,
     "time": 2022-08-25T16:58:14.000Z,
     "type": 0,
   },
   Object {
-    "az": 193.81307114785773,
-    "el": -0.03284642331569769,
-    "maxElPass": 0.09468940062113852,
-    "rng": 2331.5278975783554,
+    "az": 3.382676224927582,
+    "el": -0.0005732782426437735,
+    "maxElPass": 0.09468940060916482,
+    "rng": 2331.5278976216196,
     "time": 2022-08-25T17:05:13.000Z,
     "type": 2,
   },