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Image calibration and Threshold VIs

Hallo,

I have a picture with circular dots and I want the VI to detect them for calibrating an image. 

Now I have a VI but it doesnt work as it should. I think the problem is creating a good binary image for the VI IMAQ calibration target to points circula dots. I think I don´t understand how exactly the VIs Local Threshold and Particle Filter works.

 

This shows the calibration image and the distorted image. http://imgur.com/a/EfQCI

 

Here is my VI: http://imgur.com/4LnmzkP

 

This is the (wrong) result: http://imgur.com/rvrptBH

 

Hope someone can find the failure or give me good advices

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Message 1 of 6
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there is some problem here
first your image angles and distortion are so complicate
second you use use dot foe just area of image so calibration in other place will be encounter mistake
I recommend two thing to do
1 change camera angle to make problem more simple
2 focus on ROI by lens or extract ROI before exert calibration functions on image

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Message 2 of 6
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Hallo Hatef.fouladi,

 

thank you for your answer!

I´ve already done an extraction of the area, but it´s not better.

When I do the whole thing with the "NI Vission Assistant", the result is very good. So it has to be possible with this angle.

I think the problem is, that Labview doesn´t recognize the dots exactly. But why? How can I make this better?

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Message 3 of 6
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use some threshold function to make your dot clear
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So you want to implement in your LabVIEW application what the Calibration Training Interface does?

Which calibration method do you plan on using?

I would recommend using a grid that cover most of your field of view, instead of just your object if you can.

 

Christophe

 

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Message 5 of 6
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It works!

 

I found a function, which makes it very easy doing a threshold and perspective calibration in one function: IMAQ Learn Calibration Template.

It´s an old Labview VI which is not included in Labview 2015. I don´t understand why they deleted it!? It´s very useful.

 

Here is the result and my code:

http://imgur.com/a/Vm7c4

 

 

Thank you guys for your help 🙂

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