Undistort frames from LF camera

[dallen-28]

Hello everyone,

I am hoping to get some help with a problem I am having regarding undistortion of frames from the Left Front VLC camera. I have tried using matlab and opencv with a checkerboard pattern as well as the circular pattern with the RobVisLab toolbox. I have also obtained the intrinsic matrix and distortion parameters from microsoft's psi repo but none of the methods seem to fully capture the extent of distortion in the image, especially around the corners. I have captured images of a ball-tip stylus which should appear as a circle in the image assuming the frames were undistorted properly, but the circle still appears elongated. The most recent calibration output I have gotten from matlab is:

intrinsicMatrix =
[371.470529979248 0 0
0.813865090953600 370.066981136707 0
238.113893529264 324.787333783002 1]
Radial Distortion = [-0.0230812382805120 0.0563484441922454 -0.0273127788552269]
Tangential Distortion = [-0.00180022797353495 0.00276229915779209]
Skew = 0.813865090953600

Undistorting the frames using these parameters has negligible effects, with the elongation of the circle still seen (shown below)
Distorted:

Undistorted:

Does anyone have any insight into this problem?

Regards,
Daniel Allen