pattern matching qeustion: when camera is not perpendicular to the object

[yhs]

Dear all,

i m new in NI vision. I have already created a program to do pattern matching, and hope to obtain the rotation angle.

my problem is: when  the object rotates in any angle greater than about 20°,  I cannot get an accurate angular measurement.

I assumed that it might because my camera was not perpendicular to the surface of the object. could any of you nice guys give me some advices,please. 

thanks in advance

[Silver_Shaper]

Hi

Post your image so that give you a best practices.

[yhs]

Hi, Sasi.B

the arrowheads will point to certain direction. I hope use the template to obtain a rotation angle, but as you can see the match info could not provide a reliable angular measurement.

i have no idea how to get the direction now, the camera is fixed, does it mean that pattern matching is not a good choice in this situation?

thanks for your time

[lcady · Accepted solution]

Just use the arrow as a generic object.  Place a fiducial make inside it, and find the relation between the arrow and the fiducial.  I edited your pics to place a hole in the top of the arrow.  The VI finds the arrow as a bright object.  It uses the bounding box as the search region to find the hole.  The center of the arrow and the center of the hole form a line that points in the same direction as the arrow.  The VI and sample images are attached.

[yhs]

Hi, lcady

thank you very much, i didn't think about modify the template, this is really what i need

again, thanks for your time, have a lovely day.

yhs