1. Separate FOV, projection and distortion
FOV describes angular coverage. Projection describes how scene angle maps to image height. Distortion describes deviation from a chosen reference model. A fisheye lens can intentionally use a non-rectilinear projection while still being well controlled.
State the intended projection or calibration model instead of requesting only a maximum distortion percentage.
- Horizontal, vertical and diagonal FOV
- Reference projection model
- Allowed mapping residual
- Monotonic angle-to-pixel behavior
2. Allocate pixels where the system needs them
Ultra-wide optics compress large scene angles into a finite sensor. The distortion strategy determines how many pixels represent objects near the vehicle, at the horizon and in overlap zones.
Define important regions with the perception and stitching teams. A curve that looks visually natural may not be the curve that best supports detection or seam quality.
- Near-field ground coverage
- Horizon and object-recognition region
- Camera overlap zones
- Pixels per angular interval
3. Protect peripheral image quality
AVM images depend heavily on the outer field, where aberrations, relative illumination and color shading are hardest to control. MTF should be reviewed at field points connected to stitching and detection, not only at the center.
Edge sharpness, lateral color and relative illumination interact with ISP correction. Agree on what is corrected optically, what is corrected digitally and what variation the algorithm can accept.
- Peripheral sagittal / tangential MTF
- Relative illumination at useful field
- Lateral color and color shading
- Optical versus ISP correction budget
4. Specify calibration repeatability
A nominal distortion curve is not enough if production lenses vary in mapping, optical center, tilt or effective focal behavior. These variations can change calibration residuals and seam positions.
Link lens tolerances and camera assembly tolerances to calibration limits. Include temperature and mechanical stress when they can move the mapping.
- Distortion-curve repeatability
- Optical center and image tilt
- Camera pose and assembly variation
- Temperature-dependent calibration residual
5. Evaluate the complete surround-view chain
The lens, cover glass, sensor, ISP, calibration model and stitching algorithm form one imaging system. Review representative images and quantitative mapping data together.
Before SOP, validate multiple cameras and production-representative units in day, night, wet, high-contrast and environmental conditions relevant to the vehicle location.
- Lens-to-algorithm mapping data
- Multi-camera overlap and seam review
- Day / night / wet-scene images
- Production-representative validation