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11-15-2012 10:03 AM

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I want to apply a affine transformation on a image. I know some (at least 3) points on the current image and the same points on the "new image" (after the affine transformation).

I can not use the function from matlab or opencv to perform the geometric operation and only find basic operation like rotation or translation in the vision module

11-16-2012 10:50 AM

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You should look at the calibration functions. An affine transform is a subset of the perspective transform that the calibration functions provide.

Kevin

11-23-2012 03:01 AM

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Thanks for your answer.

I actually manage to implement in labview the transformation affine and the estimation of its matrix, once I really understand the bilinear interpolation

11-29-2012 07:01 PM

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Sometimes it is easier to work with image in the form of 2D array (especially if you are working with grayscale image).

In that case Functions>>Mathematics>>Geometry pallet should be exactly what you need.

www.xinstruments.com - Custom Software for Industrial Automation

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06-10-2015 04:12 AM

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Do you have a VI fo the affine tranformation? for 3 points?

06-19-2015 10:08 AM

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@ilanm wrote:

Do you have a VI fo the affine tranformation? for 3 points?

Maybe kl3m3n posted something you're looking forward: https://decibel.ni.com/content/blogs/kl3m3n/2015/04/24/homography-mapping-calculation-labview-code

06-22-2015 04:48 AM

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Hello,

write the equation for affine transformation and solve it. You need 3 point pairs for this. If you have more points, you could use a least-squares approach.

If you don't like coding, you can use OpenCV's functions **getAffineTransform()** and **estimateRigidTransform()**, respectively. Just perform a .dll call - there are a lot of examples online.

Best regards,

K

https://decibel.ni.com/content/blogs/kl3m3n

"

06-23-2015 02:15 AM

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Hello,

to help you a bit further, here is an example of calculating the affine transformation (least square), provided you know the three corresponding point pairs.

Hope this helps.

Best regards,

K

https://decibel.ni.com/content/blogs/kl3m3n

"

06-02-2020 01:51 AM

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Exactly what I was looking for. Thank you!