Support Orbit visualization for MEO and GEO satellites

Related #63
Flowm · Mar 21, 2023 · 667c7c2 · 667c7c2
1 parent 3de7572
commit 667c7c2
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Showing 2 changed files with 21 additions and 11 deletions.
diff --git a/src/modules/SatelliteEntityWrapper.js b/src/modules/SatelliteEntityWrapper.js
@@ -29,9 +29,10 @@ export class SatelliteEntityWrapper extends CesiumEntityWrapper {
     this.createPoint();
     // this.createBox();
     this.createLabel();
-    if (this.props.orbit.orbitalPeriod < 60 * 12) {
-      this.createOrbit();
-      this.createOrbitTrack();
+    this.createOrbit();
+    this.createOrbitTrack();
+    if (this.props.orbit.orbitalPeriod < 60 * 2) {
+      // Ground track and cone graphic are optimized for LEO satellites
       this.createGroundTrack();
       this.createCone();
     }
@@ -42,11 +43,11 @@ export class SatelliteEntityWrapper extends CesiumEntityWrapper {
     this.defaultEntity = this.entities.Point;
 
     // Add sampled position to all entities
-    this.props.createSampledPosition(this.viewer.clock, (sampledPosition) => {
+    this.props.createSampledPosition(this.viewer.clock, (sampledPosition, sampledPositionInertial) => {
       Object.entries(this.entities).forEach(([type, entity]) => {
         if (type === "Orbit") {
-          entity.position = this.props.sampledPositionInertial;
-          entity.orientation = new Cesium.VelocityOrientationProperty(this.props.sampledPositionInertial);
+          entity.position = sampledPositionInertial;
+          entity.orientation = new Cesium.VelocityOrientationProperty(sampledPositionInertial);
         } else if (type === "SensorCone") {
           entity.position = sampledPosition;
           entity.orientation = new Cesium.CallbackProperty((time) => {

diff --git a/src/modules/SatelliteProperties.js b/src/modules/SatelliteProperties.js
@@ -90,14 +90,23 @@ export class SatelliteProperties {
   }
 
   createSampledPosition(clock, callback) {
+    // Determine sampling interval and number of samples based on orbital period
+    // For improved performance use 180 sampled positions per orbit
+    const samplingInterval = (this.orbit.orbitalPeriod * 60) / 180;
+    const samplingRefreshRate = 60 * 15;
+    // Propagate a full orbit forward and half an orbit backwards
+    const samplesFwd = Math.ceil((this.orbit.orbitalPeriod * 60) / samplingInterval);
+    const samplesBwd = Math.ceil(((this.orbit.orbitalPeriod * 60) / 2 + samplingRefreshRate) / samplingInterval);
+    // console.log("createSampledPosition", this.name, this.orbit.orbitalPeriod, samplesFwd, samplesBwd, interval);
+
     let lastUpdated;
-    lastUpdated = this.updateSampledPosition(clock.currentTime);
-    callback(this.sampledPosition);
+    lastUpdated = this.updateSampledPosition(clock.currentTime, samplesFwd, samplesBwd, samplingInterval);
+    callback(this.sampledPosition, this.sampledPositionInertial);
     clock.onTick.addEventListener((onTickClock) => {
       const dt = Math.abs(Cesium.JulianDate.secondsDifference(onTickClock.currentTime, lastUpdated));
-      if (dt >= 60 * 15) {
-        lastUpdated = this.updateSampledPosition(onTickClock.currentTime);
-        callback(this.sampledPosition);
+      if (dt >= samplingRefreshRate) {
+        lastUpdated = this.updateSampledPosition(onTickClock.currentTime, samplesFwd, samplesBwd, samplingInterval);
+        callback(this.sampledPosition, this.sampledPositionInertial);
       }
     });
   }