User`s manual

STH-MDCS USER’S MANUAL 2001 VIDERE DESIGN
9
4.6 Range Resolution
Range resolution is the minimum distance the stereo system can distinguish.
Since stereo is a triangulation operation, the range resolution gets worse
with increasing distance from the stereo head. The relationship is:
d
bf
r
r ∆=∆
2
,
where b is the baseline between the imagers, f is the focal length of the lens,
and
d∆ is the smallest disparity the stereo system can detect. For the STH-
MDCS/-C, b is 90 mm, and
d∆ is 0.375 um (pixel size of 6.0 um, divided
by the interpolation factor of 16).
Table 2 plots this relationship for several focal lengths. At any distance, the
range resolution is inversely proportional to the focal length.
4.7 Field of View
The field of view is completely determined by the focal length. The
formulas for the FOV in horizontal and vertical directions are:
)/84.3arctan(2 fHFOV =
)/88.2arctan(2 fVFOV =
where f is in millimeters. For example, a 3.5 mm lens yields a horizontal
FOV of 95.3 degrees. This is about the smallest practical focal length for
the STH-MDCS.
The following table shows the FOV for some standard focal lengths.
Figure 4-1 Range resolution in mm as a function of distance, for
several different lens focal lengths.
Lens focal length Horizontal FOV Vertical FOV
3.5 mm 95.3 deg 78.9 deg
6.0 65.2 51.3
12 35.5 27
16 27 20.4
Table 2 Horizontal and vertical field of view for different
lens focal lengths.