how to refine the extrinsic parameters of fisheye camera?

Hi everybody:

I have had the intrinsic parameters of a fisheye camera. when I'm calibrating the extrinsic paramters of fisheye camera by using the build-in function of extrinsics(), I found the accuracy is not high. After i looked the source code of extrinsics(), i found it does not refine extrinsic paramters. So, my question is as follows:

1. how can i refine the extrinsics paramters?

2. can i use LM optimiztion algorthm refine the extrinsics? how to use?

has anybody give a hint ?

thank you!

[Bjorn Gustavsson]

What is your use-case. For one type of use I have a reasonably good tool.

[Ron Leonard]

the use-case as follows:

I have four fisheye camera on a vehicle model. i got the bird's eye view of every camera based on the same virtual camera on the top of the vehicle's center. then , i stiching the four bird's eye view.

cause the stitching results is not very perfect. so i want to improve the accuracy of the camera extrinsic parameters.