Vision Sensor SBSI/SBSC-EN, 8062650 - 1607b - 13/09/2016
Page 77
Vision Sensor Manual
Parameter
Function
be set.
Also different read only paremters, as well as deviation parameters are
shown in this dialog (see also:
Calibration, Calibration parameter (Page 70)
Start Calibration
Calibration is started. All visible points of tht calibration plate are
determined, all detected are marked, and calibration is calculated.
Test point
A test point can be set in the image, whose world coordinate values for
test and control purposes are displayed in the Test point window.
">" / "<"
Go to next / previous step
Note:
The sensor can be mounted in any alignment / pose referred to the measurement plane. Anyway a close
to perpendicular alignment should be preferred, as this causes less distortion and this way less error
correction is needed.
World coordinates are not absolute. The coordinate values refer to the principal point in left, upper
corner or the field of view. Beside coordinates, distances are also calculated in world frame.
This kind of calibration is suitable for standard lenses, integrated or C-mount. It´s not suitable for
telecentric lenses.
Advices for the usage of calibration plates
l
The calibration plate must be clean and plain.
l
The plate must be illuminated homogeneously over the entire field of view and must not be
overexposed. The bright regions should have a grey value of at least 100 and below 255. The contrast
between bright and dark regions should be at least 100 grey values. That means, the image / any region
must not be over- or underexposed.
l
The entire field of view must be covered by the calibration plate. Anyway, for a successful, precise
calibraiton it´s not necessary that the whole plate / all points of the plate are visible. It is sufficient if
approximately a quarter of the plate is visible like shown below (always including the center of the
plate with the pattern of points with smaller black point in their center).
l
Calibration does work correct only if focus and position of the sensor does not change in relation to
the measurement plane.
Summary of Contents for SBSC-EN
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