Proxima ASA STH-MD1/-C ユーザーズマニュアル

STH-MD1 U

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ANUAL

 

 

 

 

 

 

 

 

 

 

 

 

 

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2001 V

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ESIGN

 

9 

chooses the focal length based on the narrowest field of view acceptable for 
an application, and then takes whatever range resolution comes with it. 

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: 

?

?

?

2

, 

where  b is the baseline between the imagers,  f  is the focal length of the 
lens, and 

?

is the smallest disparity the stereo system can detect.  For the 

STH-MD1/-C,  b  is 90 mm, and 

?

is 0.46875 um (pixel size of 7.5 um, 

divided by the interpolation factor of 16).   

Figure 4-1 plots this relationship for several focal lengths.  At any distance, 
the range resolution is inversely proportional to the focal length. 

 

 

The field of view is completely determined by the focal length.  The 
formulas for the FOV in horizontal and vertical directions are: 

)

/

8

.

4

arctan(

2

?

 

)

/

8

.

3

arctan(

2

?

 

where f is in millimeters.  For example, a 4.8 mm lens yields a horizontal 
FOV of 90 degrees.  This is about the smallest practical focal length for the 
STH-MD1. 

The following table shows the FOV for some standard focal lengths. 

 

 

 

4.8 mm 

90 deg 

73 deg 

8.5 

57 

44 

12.5 

50 

38 

16 

22 

17