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For lenses with higher distortion orders, more images may be required, and it becomes even more important to take grid

images where points are present in the corners of the field of view. As many as 30 images may be required to accurately

estimate 3

order distortions.

Complex distortion setups involving cameras imaging through refractive interfaces (such as through glass and water) can be

modelled using the Variable Ray Origin (VRO) option. Using VRO 4

order is recommended unless the setup involves

multiple refractive interfaces.

HIGH-MAGNIFICATION CALIBRATION

For macro lenses and small fields of view, it will become very difficult to get significant off-axis tilt in the target without

severe defocus. Because of this, the “center” values may be poorly estimated. The best remedy is to attempt to get as much

tilt as possible to get a better estimate, but failing this, the High magnification option will force the center values to be the

numerical center of the lens.

INTERPRETING CALIBRATION RESULTS

After the calculation is complete, you will be presented with a report of calibration results and error scores. The errors will

be displayed per image, as well as an overall error score:

The overall error (Standard deviation of residuals for all views) should be displayed in green. If you have a good set of

calibration images with good tilt and coverage of the image field, and the score is green, then the calibration is good and

you can click Accept to finish.

If the score is displayed in red, you may need to remove some images or recalibrate. Vic-3D will automatically remove very

poor images, but you can remove additional images by right-clicking in the table of scores and selecting Remove row.

If the result is uniformly high and not due to just a few outliers, or if you have several high scores, there may be a problem

with the setup. Check that:

• The grid images are in focus.

• The exposure times are short enough to eliminate motion blur.

• The cameras are secure on the stereo rig.

Correlated Solutions Vic-3D v7 User Manual

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