Real-time geofencing monitors millions of mobile devices entering, lingering in, or exiting designated geographical boundaries.

1. Spatial Indexing Algorithms

  • Uber H3 Hexagonal Grid: Discretizes Earth into regular hexagonal cells across 16 hierarchical resolutions. Adjacent cells maintain identical center-to-center distances, eliminating distortion in radius queries.
  • Google S2 Spherical Projections: Projects Earth onto a cube subdivided with Hilbert space-filling curves, providing lightning-fast 64-bit integer spatial containment checks.
  • Point-in-Polygon (PIP) Ray Casting: Evaluates vector intersections for arbitrary polygonal boundaries, offering exact precision at higher CPU computational overhead.