【位姿测量】可能影响畸变参数的若干因素
1 镜头焦距与畸变
镜头畸变实际上是光学透镜固有的透视失真的总称，这是透镜的固有有特性（凸透镜汇聚光线、凹透镜发散光线），所以无法消除，只能改善。
一般情况下，定焦镜头焦距越长畸变越小，而焦距越短畸变就越大，这是一个普遍的规律。
结论1：5mm镜头制作的凸透镜较凸，畸变相比长焦镜头就较大。
2 标的板到相机的距离与畸变
使用同一尺寸标定板，其到相机距离越大，标定的畸变误差越大
说明 在定板其到相机距离约3米处，标定结果
———GigE 640*480 3米处RD=36度 17张——————————————————
Calibration results after optimization (with uncertainties):
Focal Length: fc = [ 1357.60854 1357.18983 ] +/- [ 85.11549 89.95822 ]
Principal point: cc = [ 310.27360 235.77096 ] +/- [ 30.23387 52.62672 ]
Skew: alpha_c = [ 0.00000 ] +/- [ 0.00000 ] => angle of pixel axes = 90.00000 +/- 0.00000 degrees
Distortion: kc = [ -0.92342 56.99526 0.00568 0.00929 0.00000 ] +/- [ 0.82282 95.70305 0.02560 0.01764 0.00000 ]
Pixel error: err = [ 0.12885 0.14505 ]
Calibration results after optimization (with uncertainties):
Focal Length: fc = [ 1310.93673 1303.41820 ] +/- [ 115.82343 122.00456 ]
Principal point: cc = [ 332.55936 280.59292 ] +/- [ 60.46272 104.38031 ]
Skew: alpha_c = [ 0.00000 ] +/- [ 0.00000 ] => angle of pixel axes = 90.00000 +/- 0.00000 degrees
Distortion: kc = [ -1.25144 19.27384 -0.03045 -0.00243 0.00000 ] +/- [ 0.93982 45.69784 0.05036 0.02553 0.00000 ]
Pixel error: err = [ 0.19194 0.22989 ]
Calibration results after optimization (with uncertainties):
Focal Length: fc = [ 1366.92068 1357.02520 ] +/- [ 128.37988 135.14877 ]
Principal point: cc = [ 378.81748 327.52591 ] +/- [ 97.01870 138.19026 ]
Skew: alpha_c = [ 0.00000 ] +/- [ 0.00000 ] => angle of pixel axes = 90.00000 +/- 0.00000 degrees
Distortion: kc = [ -1.04793 7.35841 -0.03638 -0.01154 0.00000 ] +/- [ 0.78238 18.06966 0.04522 0.02735 0.00000 ]
Pixel error: err = [ 0.19024 0.23904 ]
Calibration results after optimization (with uncertainties):
Focal Length: fc = [ 1360.80596 1359.38824 ] +/- [ 93.12630 98.16594 ]
Principal point: cc = [ 297.97237 213.16403 ] +/- [ 20.13163 30.87725 ]
Skew: alpha_c = [ 0.00000 ] +/- [ 0.00000 ] => angle of pixel axes = 90.00000 +/- 0.00000 degrees
Distortion: kc = [ -1.69108 171.80165 0.00253 0.00132 0.00000 ] +/- [ 1.19203 225.67375 0.02194 0.01704 0.00000 ]
Pixel error: err = [ 0.14302 0.17264 ]
——————GigE 640*480 20c 1m 20(mm设置标定) 手标20———————————
Calibration results after optimization (with uncertainties):
Focal Length: fc = [ 1324.52127 1323.22602 ] +/- [ 14.62928 14.92838 ]
Principal point: cc = [ 276.13262 242.73589 ] +/- [ 11.65359 11.55802 ]
Skew: alpha_c = [ 0.00000 ] +/- [ 0.00000 ] => angle of pixel axes = 90.00000 +/- 0.00000 degrees
Distortion: kc = [ 0.11382 -2.44772 -0.01226 -0.01014 0.00000 ] +/- [ 0.07897 3.40545 0.00400 0.00391 0.00000 ]
Pixel error: err = [ 0.11169 0.11500 ]
结论2：在距相机不同距离标定的畸变不同，3米处用相同的20张图片多次标定出畸变也不同，故较远时畸变不易标定准确，畸变矫正模型对位置的误差较小贡献也较小。
3 在视场的不同位置，畸变不同
凸透镜不同位置制作的工艺不完全标准，聚光状况不同，对不同视场位置的图像畸变不同
结论3：同视场位置的图像畸变不同
4标定板大小（标定板相对视野大小）与畸变
5高分辨率与畸变
高分辨率可以扩大视角，在满足相同视场（1.5米*1.5米）情况下，其距相机位置将减小(3米减到1.6米)，进而相机畸变减小。