Two major measurements are being considered, one is about image
position and the other is about image intensity.
For the former, new techniques have been developed to compensate for
both radial and
tangential distortions in a camera lens and to determine the spatial
relationships between the camera and the 3-D world. The experiments have
shown that the distortion compensation leads to a significant improvement in
accuracy. A new normalized measurement has been introduced that can be
used to objectively evaluate and compare the accuracies of various calibration
techniques, despite the parameter differences among the camera systems.
Intensity calibration is necessary because of the peripheral attenuation
in images due to optical lens, whose effect typically results in darker corners
in images. We have developped a model for such pheriphral
attenuation. An intensity calibration method has also been developed
to compensate the intensity pheriphral attenuation.
S. Chen and J. Weng,
``Calibration for peripheral attenuation in intensity images,''
in Proc. First IEEE International Conference on Image Processing,
Austin, Texas, pp. 992-996, Nov. 13-16, 1994.
J. Weng, P. Cohen and M. Herniou, ``Camera calibration
with distortion models and accuracy evaluation,''
IEEE Transactions on Pattern Analysis and Machine Intelligence,
vol. 14, no. 10. Oct. 1992, pp. 965-980.
To Weng's Home Page: http://web.cps.msu.edu/~weng/