Corner Extraction？？？？？/

[nongnong]

My object is a cuboid. And I wonder if there is the function of realizing the  Corner Extraction in IMAQ? just the corners, not asking the all edge lines

[GuenterMueller]

Hello nongnong.

What about teaching the corners (and some area around it) and using a pattern match? (This should work fine if you have a homogenous background.)

Best regards, Guenter

[nongnong]

Hi,Guenter

your seggest may be feasible. And I will have a try.

Here I have another question: If I use pattern match, is it feasible too when the object changes? or is one kind of pattern match just for one object?

[GuenterMueller]

Hello nongnong.

Pattern matching is even powerful if the objects look slightly different than the template. The match is indicated by a score. The higher the score (An exact match is reported by a score of 1000 which indicates a 100% match.), the better the match.    On the other hand, you can configure pattern matching to find lots of nonsense (e.g. by requesting matches that have a low score, etc.).   

Teaching a good template is very important and frequently underestimated. You may want to "educate" your eyes to recognise good candidates. The IMAQ Vision examples are quite helpful as they allow you to load an image, define a template interactively and search for it. This will assist you in deciding whether pattern matching is an option for your application.
The NI Vision Concepts Manual also handles the subjects Pattern and Geometric Matching.

Regards, Guenter