Adept AdeptSight User Guide - Manual (Page 643)

Gain and Black Level should be adjusted after the camera Exposure has been set for max-
imum contrast.
Vision Basics - Camera Calibration and Lighting
Camera Calibration
Camera calibration is the process of relating the image size of the camera to the actual size of
the field of view. Two primary pieces of information are established when camera calibration
is run:
l
The number of pixels needed to see a millimeter of distance in the field of view
This relationship is used by any tools that make distance measurements. It is also
used by vision-guided motion devices.
l The ratio of the height of a pixel to its width
See Standalone Camera Calibration on page 207.
NOTE: The offset of the camera from the robot or other equipment is not part of this cal-
ibration. That information is obtained after the standalone camera calibration. See Cal-
ibrations on page 51.
Some important points to remember about camera calibration:
l The millimeter-to-pixel ratio is different for different camera-to-object distances. If
you are making distance measurements of objects that are different distances from
the camera, you have to create a calibration data set (virtual camera) for each dis-
tance.
l
When you change the focus of a camera lens, the amount of the viewing area in the
field of view changes. This means that the millimeter-to-pixel ratio changes, and cam-
era calibration created before the lens was refocused are not valid. The camera must
be recalibrated.
Lighting
Type Advantages Disadvantages
Incandescent Inexpensive, can be cycled Short life (for AC lamps), heat
Fluorescent Efficient, cool Cannot be cycled, flickers
Tungsten-Hal-
ogen High output Heat, can’t be cycled
Gas Strobes High power, freezes motion Expensive, poor CCD sensitivity
IR Laser Good CCD sensitivity Highly divergent, federally reg-
ulated
Vision Basics - Camera Calibration and Lighting
AdeptSight User's Guide, Version 3.2.x, Updated: 8/23/2012
Page 643