omnidirection camera model or opencv fisheye model

[Mediumcore]

Hello,thanks for great work. But i wander what camera model you are used for fisheye model ,It's opencv fisheye KB model or ocam model? Your background pdf doc present the mei ocam model, but i can't see the xi parameter used for ocam model. Does the [k1,k2,p1,p2] come from radial-tangential distortion model?And with ocam model. Do you neglect the xi parameter from ocam model? My wechat is 18811720989, expect for your join with me ,share some ideas.Thanks.