SIPLACE Vision Customer_en - 第139页
SIPLACE Vision - T eaching Fiducials Synthetic Fiducials for Position Rec ognition Applications Fiducial shapes S tudent Guide SIPLACE Vision (Customer) Edition 12/2008 EN SIPLACE Vision - T eaching Fiducials 139 With Su…
SIPLACE Vision - Teaching Fiducials
Fiducial shapes Synthetic Fiducials for Position Recognition Applications
Student Guide SIPLACE Vision (Customer)
SIPLACE Vision - Teaching Fiducials Edition 12/2008 EN
138
6.2.1.5 Algorithm Setting
In contrast to the algorithm settings for ICOS, measuring methods can not be selected or deselected
here.
In the SIPLACE Vision method, you can only change parameters or quality thresholds.
6-7: Algorithm setting shown with cross fiducial as example
The Minimum recognition quality of 70% is set so that no fiducial shape faults will lead to incorrect
calculation of the fiducial reference position and therefore to a placement offset.
Contrast type ’1’ indicates a light fiducial on a dark background. If you evaluated a dark fiducial on a
light background, contrast type ’-1’ would be shown.
The minimum number of image pairs can be increased or reduced in steps of 8. The default value
is 64. The cross-shaped fiducial has 8 image pairs for the edge on one side of the cross. If similar
structures are expected near the fiducial area, in the camera field of vision, the number of image pairs
should be increased accordingly to ensure reliable recognition of the shape.
SIPLACE Vision - Teaching Fiducials
Synthetic Fiducials for Position Recognition Applications Fiducial shapes
Student Guide SIPLACE Vision (Customer)
Edition 12/2008 EN SIPLACE Vision - Teaching Fiducials
139
With Subsampling the system combines a number of point pairs to one evaluation point or a so-called
moxel. The number indicates how many points are summarized on each page to facilitate faster
calculation. The fine structure (extremely thin bar widths) setsthis parameter to its standard value.
The Distance between points is set to the respective default value through the tolerance setting for the
fine structures.
This changes the distance between the points for the light foreground and dark background.
6-8: Minimum difference in contrast
Minimum contrast is set to ’20’ as a default,
meaning that a contrast difference between purple
and blue in the pseudo colors image is enough for
that structure to be recognized as a possible
fiducial contour. (concealed fiducial (blue) 39-55 /
background purple 15-20)
6-9: Fine search step for cross fiducial
Edge quality
The edge quality value for many interfering
structures can be set from 2 (default value) to 1.
this means that the edge is determined more
precisely. This also means that interfering
structures on the edge influence the measuring
result, since the permitted tolerance is very low.
If interference can be detected on the fiducial edge
(1), this parameter can be set to a value of 5. This
robust measurement method determines the edge
positions for the fine search with a greater
permitted tolerance or without checking (value 5)
the tolerance value for the edge position. (This
should be shown by the parameter ’Robust’ –
"Inaccurate".)
SIPLACE Vision - Teaching Fiducials
Fiducial shapes Sample Fiducials for Position Recognition
Student Guide SIPLACE Vision (Customer)
SIPLACE Vision - Teaching Fiducials Edition 12/2008 EN
140
The effect on fine centering can be shown on an ellipsoid, programmed as a circle. The edge quality is
changed from left to right, from a value of 1 to 3.
Legend
1. Edge quality 1: 22 scan lines not in tolerance range.
2. Edge quality 2: 16 scan lines not in tolerance range.
3. Edge quality 3: all scan lines OK
As can be seen in the diagrams, the circle diameter recognized is larger due to the higher permitted
tolerances (clearly seen in the differences between diagrams 2 and 3).
6.2.2 Sample Fiducials for Position Recognition
The sample fiducials are learnt interactively by the system, during programming. The following
procedures are performed:
The evaluation area for the fiducial shape is defined by the operating personnel.
The fiducial reference point (usually the fiducial center point) is searched for by the Vision system.
If the fiducial reference point can not be found or if the coordinates defined for the fiducial shape are
unusual, the operator can click to define the fiducial reference point manually and then let the system
learn the fiducial shape.
The parameters and coordinates learnt by the Vision system can NOT be subsequently manually
changed. In this case, the fiducial has to be retrained (repeat procedure).
NOTE:
Sample fiducials do not support the function for rotating the PC orientation in the placement
recipe.