Calibrating Camera - ABB PickMaster Twin - PowerPac Applications Manual

4 Working with PickMaster PowerPac

4.3.8 Calibrating camera

4.3.8 Calibrating camera
Introduction
Overview
The camera calibration defines the origin for the coordinate system shared by the
camera and the robot base frame or work object. If the camera is used with a
conveyor work area the camera calibration must be performed before the base
frame calibration because the camera calibration origin works as a common
reference point for the two calibrations. When a camera calibration is done, the
origin is saved and the user can graphically display this origin when the base frame
calibration is performed.
Checkerboard calibration
The camera calibration method is called checkerboard calibration. The calibration
is performed in two steps. First the whole image is analyzed and warped into a
correct image and then the region of the resulting image is defined.
The algorithm uses the scale in the center of the image, which means that it makes
all the tiles the same size as the tile at the center of the original image.
Multi-view calibration
The camera can be calibrated using one or several images. Multi-view calibration
can compensate for parallax error.
The accuracy of the multi-view calibration increases with the number of input
images. Use at least three images at different tilt angles and altitudes. Using multiple
images of calibration plates in parallel planes does not increase accuracy.
Prerequisites
Camera calibration is done using calibration papers that you must print out. The
calibration papers are found in the PickMaster package.
The printed image must have a high contrast and the paper must not be reflective
(high gloss). Verify with a ruler that the squares are proportional. If the square
width or height differs from 10 mm, make a note of the actual measures.
The calibration paper must be adequately illuminated and free from shadows.
If a conveyor is used, the x-axis of the calibration paper must be aligned with the
motion of the conveyor.
Calibrating the camera
The Camera Calibration dialog can be used to handle camera calibrations for the
specified camera. Calibrations can be created, edited, imported, and exported.
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Note
If any firewall or antivirus software is installed, add pickmasteru.exe,
sshd.exe, and visionclient. exe to the white list.
Otherwise the PickMaster PowerPac cannot connect Runtime and the vision
function cannot work normally.
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Application manual - PickMaster® Twin - PowerPac
3HAC064218-001 Revision: B