I built an iOS app for taking photos of the same location from the same angle over extended periods.
The technical approach: - First shot captures GPS + compass bearing + device tilt as the reference - Frame Lock uses CoreLocation + CMMotionManager to guide return visits - Ghost Overlay composites the previous shot for manual alignment - Backend uses SuperPoint + SuperGlue for ML-powered sub-pixel alignment - Async job system for alignment and timelapse generation
Offline-first architecture with SwiftData. Photos capture locally, sync when online.
Public stacks are collaborative—anyone can contribute shots to document a place together.
Landing page: https://stack.photos TestFlight: https://testflight.apple.com/join/YfqCPu6w API docs: https://api.stack.photos/docs