calibrating camera outside of mvSDK

[han-so1omon]

Trying to use the bottom facing cam on snapdragon flight for optic flow outside of mvSDK. I'm not sure what the parameters in the fisheye model calibration represent or how to use them in the undistortion. I skimmed thru S.Shah's paper but couldn't figure it out. Specifically, if the first four params are k1-4, then what are the four trailing zeros?

Secondly, would it be correct to call the following to retrieve the flat plane image?

cv::fisheye::undistortPoints( distorted=capturedImagePts, undistored=flatImagePts, K=KFromCamMgrParams D=DFromCamMgrParams, R=noArray(), P=noArray());

Last, to verify:
Is the image from qcamvid optic flow cam original image or undistorted image?