Tips for Vision Calibration
Field of View of Cameras
A large field of view increases mm/pixel (length of 1 pixel) value and decreases detection accuracy of the workpieces.
If the following values from the calibration result do not satisfy the required accuracy,
- XmmPerPixel (X mm of one pixel)
- YmmPerPixel (Y mm of one pixel)
consider the following methods.
- Reinstall the camera and the workpiece to shorten the work distance (distance from the lens to the object)
- Use a high resolution camera
- Use a high resolution lens (e.g. our mega pixel lens) or a long-focal-length lens.
KEY POINTS
For details on the vision calibration, refer to the following manual.
"Vision Calibration" in "Vision Guide 8.0 Software"
Deviation and Tilt of the Field of View
If Error (deviation) or Tilt values displayed in the calibration result were more than "1", it can be considered that calibration was not done properly.
For details, refer to the following manual.
"Vision Guide Software-[ Calibration Complete Dialog Box"
Dialog displaying the calibration results
Reference Point Detection
For the vision calibration, use a proper combination of the reference point and the vision object; for instance, use a perfect circle as a reference point and detect it by the Blob object. In addition, it is necessary to perform a calibration with the “aperture” and “focus” of the camera adjusted to the workpiece.
- Adjust the camera aperture not too bright and not too dark in order to detect edges and marks of the workpiece.
- Adjust the focus to see the workpiece sharply. Blurs may affect the detection rate and accuracy.
KEY POINTS
If the workpiece is thick and the top face does not come into the focus when the focus is placed on the conveyor, adjust the focus to the top face and set the reference point at the same height to calibrate.
For details on reference points, refer to the following manual:
"Vision Guide 8.0 Software- Reference Points and Camera Points"
For details on vision objects, refer to the following manual:
"Vision Guide 8.0 Software- Vision Objects"