OpenCV only provides Linear Kalman Filter afaik. For nonlinear estimation you need to use Extended or Unscented (this one is often used in Drone). I wrote esti

OpenCV only provides Linear Kalman Filter afaik. For nonlinear estimation you need to use Extended or Unscented (this one is often used in Drone). I wrote estimation library in Go [1] last year which implements a lot of Kalman Filter alternatives and optimisations + smoothing https://github.com/milosgajdos83/go-estimate https://github.com/milosgajdos83/go-estimate