LTI TRUCAM LASER MEASUREMENT DEVICE - Tele-Traffic

Adjusting Camera Settings
The Camera’s default settings are set for optimum results in a typical situation. You may need to adjust
some settings based upon your preference or current location.
Depth of Field
The depth of field (DOF) is a unit of measurement
that represents the range of distances within an
image where the focus is acceptably sharp. This is
the distance in front of and beyond the subject that
appears to be in focus. The DOF is determined by
the subject distance, the lens focal length and the
lens F-stop. On the TruCAM, you cannot change the
distance and the lens focal length, so only the F-stop
is variable. The TruCAM is able to adjust gain in
accordance of the aperture. During a capture session,
a larger f-number is better.
The two images to the right have the same focus, but the f-number of Figure 40(A) is 2.8 and Figure
40(B) is 16. In Figure 40(B), the DOF is much greater. In Figure 40(B) the fine branches of a small tree
a sort distance in front of the lasers camera now become visible.
Practical Note: At the time image Figure 40(B) was captured the light was very poor. To highlight
the effect of Depth of Field the F16 f-stop had to be used. As with any type of camera if a high F-stop
is employed and the light is insufficient the image takes on a dark graining effect as shown in this
example. If your images are dark with graining readjust the F-stop to clear the effect.
Iris
Iris is an adjustable aperture used to control the amount of light coming through the lens. The more
the iris is opened, the more light it lets in and the brighter the image will be. Aperture is the unit of
measurement that defines the size of the opening in the lens that can be adjusted to control the
amount of light that reaches the digital sensor. The size of the aperture is measured in F-stop. The Iris
Adjustment Ring may be positioned on an F-stop or anywhere in between two F-stops.
In any type of environment, maintain the biggest f-number possible.
The smaller the f-number, the bigger the opening (more light).
Typical value on cloudy or foggy day = 8 to 11.
The bigger the f-number, the smaller the lens opening (less light).
Typical value on sunny day = 11 to 16.
Automatic Gain Control
Automatic Gain Control (AGC) optimises picture quality at all times during the day. It increases the
video signal at low light levels to make the picture brighter. If the majority of the image is dark, AGC
will adjust the entire image to make it more easily viewable.
This option is available during the Capture Mode. Tap 
 or press the soft key to toggle
AGC ON or OFF.
If the 
 toolbar button is not displayed, tap or press the soft key.
ON: The icon is displayed at the top of the LCD Touch Screen and AGC electronically adjusts the
camera to the proper light level.
OFF: The icon is not displayed at the top of the LCD Touch Screen.
AGC cannot compensate for all lighting conditions and typically must be used in conjunction with an
adjustment of the lens iris.
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Figure 40A Figure 40B
© Tele-Traffic UK Ltd 2011