![](bg6.png)
the camera with respect to the zoom when, in practice,
the focal length in the zoom range of the camera can
vary up to a few centimeters. The consideration of
constant lens distortion for the zoom range is not true
either, although its influence in the final results might
be insignificant.
Another possible source of error is the position of the
calibration pattern in the Smart Room. The Smart
Room has some predefined points, precisely mea-
sured to put the calibration pattern on according to
arbitrary coordinates. For each attempt to position
the calibration pattern at predefined 3D world coordi-
nates, there is an error of about 0.5cm in the physical
location, which is small considering the actual dimen-
sions of the Smart Room(4m × 5m), but still enough
to affect camera calibration results.
ACKNOWLEDGEMENTS
We want to thank to Jeff Mulligan for the ideas given
in the algorithm definition and to Albert Gil for the
support given for camera grabbing software.
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