Instruction Manual

7-14 Programming Basics
13. Adjust the Search Length and Projection Length to experiment with their effect.
TIP The Search Length should be optimized so that it contains only one gray value
transition (light to dark, or dark to light). A longer caliper increases the range for
finding the corner, but also increases the chance of finding the wrong corner.
TIP Projection Length controls the averaging for the transition amplification. A
wider caliper is better for rough edges or eliminating noise caused by traces on
the board. Thinner calipers are more immune to rotated parts.
14. Set the
Edge Polarity to Light-dark.
15. Set
Minimum Contrast to 2.
> This is the lowest acceptable difference in gray-levels on opposite sides of the edge to
qualify as a transition.
16. Set
Caliper Density to 2.
> A lower value will space the calipers farther apart. A higher value will overlap them
more. You can also use fractional numbers (0.5 for example).
TIP Caliper Density controls how many calipers are used. More calipers may help
reduce the effects of edge irregularities, but will take longer to execute. You
should set the
Projection Length and Caliper Density such that you have at
least five calipers along the edge.
17. Click on
Teach.
18. Test the fiducial by clicking on
Find Fid.
> The
Test Results indicate if the fiducial was found or not, its found coordinates and
how long it took to locate the fiducial.
19. Click on
Next to save the results and end this tutorial.
This concludes the tutorial on Corner Finder.