Why does IMAQ Match Geometric Pattern return false matches?

[RPC MSOE]

Hello,

I am trying to use IMAQ Match Geometric Pattern.vi to locate a grid of circles.  Four outer circles have different radii than the inner 96 circles.  The 4 outer circles will always be in the image, however, the 96 inner circles may or may not be present.  I tried using Vision Assistant to create a template in which the 4 outer circles are present, but I used the "ignore" option to get rid of the 96 inner circles.  Whenever I attempt to find matches, they are lined up in the y-direction, but they are shifted in the x-direction.  Do you have any suggestions?  Thanks in advance.

[Meghan R]

Hello RPC,

I need to get some more information from you to be able to help you.  First of all, what versions of LabVIEW and Vision Assistant are you using.  Do you want to Pattern Match the outer circles or the inner circles?  Could you please attach a few example images, so that I can better understand what you are trying to match.  Did you create a template to use in the pattern matching?  I would like to see that as well. 

Thanks,

Meghan
Applications Engineer

[RPC MSOE]

Meghan,

I am using LabVIEW v8.0 and NI Vision Assistant v8.0.  My goal is to scan the image attachment "Original Fixture" and find the 2 identical patterns of 96 inner circles surrounded by 4 outer circles as shown in the attachment image, "Template."  I am only interested in the 4 outer circles since I would like to use the Circle Finder function to determine the radius of the 4 outer circles but not the 96 inner circles.  I used Vision Assistant to create the template in the Geometric Matching Setup .  I chose to ignore the inner 96 circles so that I was left with the 4 outer circles.  When I try to find 2 matches, one is correct, and the other is aligned horizontally, but not vertically.  Thank you for taking an interest in this issue.

RPC MSOE

[Meghan R]

RPC MSOE,

From what you are describing, Pattern Matching would be a better function to use than Geometric Matching.  Geometric Matching will search for any image that matches the template, regardless of direction.  The NI Vision Concepts Manual can help you understand these functions better.  Start>>Programs>>National Instruments>>Vision>>Documentation>>Search the NI Vision Bookshelf and then select the NI Vision Concepts Manual.

Good Luck with your application!

Meghan
Applications Engineer

[RPC MSOE]

Hello Meghan,

Thanks for all of your help.  I think I understand the difference now.

RPC MSOE