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Coordinate Frames and Units

This project uses a two-frame model to keep simulation math correct and rendering stable.

Canonical World Frame (Authoritative)

  • Frame: Standard ECEF (Earth-Centered, Earth-Fixed)
  • Axes:
    • +X: lat=0, lon=0 (prime meridian on equator)
    • +Y: lat=0, lon=+90E
    • +Z: north pole
  • Units: kilometers
  • Type: DVec3
  • Component: WorldEcefKm(DVec3)

All simulation and long-lived data (satellites, ground points, LOS, ground tracks) must use this frame.

Bevy Render Frame (Non-Authoritative)

  • Frame: Bevy world space (Transform.translation)
  • Units: kilometers (Vec3, f32)
  • Purpose: Rendering only

Conversion boundary lives in core::space:

  • ecef_to_bevy_km(DVec3) -> Vec3
  • bevy_to_ecef_km(Vec3) -> DVec3

Rule of Thumb

Never use Transform.translation as the source of truth for absolute world position.

Naming Convention

  • *_ecef_km: standard ECEF, DVec3
  • *_bevy_km: Bevy render space, Vec3