Rolling Shutter Propeller Bend Lab

Every phone camera sensor is a rolling-shutter CMOS chip: instead of exposing an entire frame in one instant, it resets and reads pixel rows sequentially from top to bottom, each row a few microseconds after the last. This simulator spins a fan with straight, rigid blades and reconstructs, row by row in real time, the photo a rolling-shutter sensor would actually capture — comparing it live against a global-shutter sensor that exposes every row simultaneously. Because each row is captured a fraction of a revolution after the last, the same straight blade is sampled at a different angle in every row, and the reconstructed photo shows it bent into a curved sickle shape — the well-known "bent propeller" artifact photographers see in phone videos of drones, ceiling fans and helicopters. Adjust the per-row readout time, sensor row count, fan speed and blade count to see the angular smear Δθ = ω·T change in real time and watch straight blades curve.