Different sensor rows capture different instants; motion during readout can distort the shape of a single frame.
Why do straight objects lean during fast camera movement? Rolling shutter
During a fast sideways move, a light pole or building edge can seem to lean. This is often an imaging-timing effect rather than a radio-link fault. A video frame is not always captured at one instant.
A frame assembled line by line
Many CMOS sensors expose or read image rows in sequence. The top and bottom rows therefore represent slightly different moments. If the camera or subject moves during that interval, the final image combines different positions. Fast lateral movement can slant vertical lines; rotating blades or wheels can appear bent or fragmented. This differs from lens distortion and from a whole frame that freezes or breaks into compression blocks.
| Appearance | Likely cause | Check first |
|---|---|---|
| Straight pole leans only during a sideways move | Row-by-row capture and relative motion | Motion, subject distance and sensor readout |
| Wide-angle edges bulge even while stationary | Lens distortion or correction | Field of view and lens settings |
| Whole frame freezes or becomes blocky | Encoder, radio or receiver instability | Bitrate, signal, antennas and receiver |
What makes it more visible?
The important quantity is how far the scene moves during sensor readout. Nearby objects change position faster in the image than distant ones. Rapid yaw, vibration and rotating subjects also increase visible artifacts. Higher frame rate alone does not guarantee that rolling-shutter distortion disappears; readout mode, exposure, motion and stabilization all influence the result.
Reducing the effect
Leave more distance from close vertical structures during fast movement, stabilize the airframe and camera mount, and test with repeatable passes by poles or a grid. For tasks involving fast-object measurement or precise geometry, consider whether a global-shutter sensor is required. Global shutter samples all pixels at the same instant and avoids this particular row-timing deformation, although ordinary motion blur can still occur.
The original illustration contains Chinese labels; its English explanation is given above. ZYRO Cam product brief