How to verify the correctness of calibration of a webcam
i am totaly new to camera calibration techniques...i am using OpenCV chessboard technique...i am using a webcam from Quantum...here are my observations and steps...
- i have kept each chess square side = 3.5 cm. It is a 7 x 5 chessboard with 6 x 4 internal corners. i am taking total of 10 images in differnet views/poses at a distance of 1 to 1.5 mtr from the webcam
- i am following the C code in Learning OpenCV by Bradski for the calibration. my code for calibration is cvCalibrateCamera2(object_points,image_points,point_counts,cvSize(640,480),intrinsic_matrix,distortion_coeffs,NULL,NULL,CV_CALIB_FIX_ASPECT_RATIO);
- before calling this function i am making the first and 2nd element along the diagonal of the intrinsic matrix as one to keep the ratio of focal lengths constant and using CV_CALIB_FIX_ASPECT_RATIO
- with the change in distance of the chess board from the webcam the fx and fy are changing with fx:fy almost equal to 1. there are cx and cy values in order of 200 to 400. the fx and fy are in the order of 300 - 700 when i change the distance.
- presently i have put all the distortion coeficients to zero because i didnot get good result including distortion coeffs. my original image looked handsome than the undistorted one!!
am i doing the calibration correctly? will i use any other option than CV_CALIB_FIX_ASPECT_RATIO? if yes which one?
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