Hough Transform & Projection Based Methods for Edge Detection

[DonRoth]

Hi Folks -

In Chapter 11 of the latest Vision Concepts Manual, there is discussion regarding the use of the hough transform and projection-based methods for edge detection.  Yet, it is not clear where or if these algorithms are actually implemented in any of the Vision edge detection VIs.  Can someone illuminate us further on this?

Thanks,

Don

[Andrey_Dmitriev · Accepted solution]

Hi, Don,

IMAQ Find Edge VI

Andrey.

[DonRoth]

I don't see these (Hough, Projection) options available in the other tools, like 'IMAQ Edge Tool 3', which is where I was looking originally.  Is a particular method used as default for this tool?

Also, is there a more complete discussion somewhere regarding using the hough transform for this purpose?

Thanks,

Don

[Andrey_Dmitriev]

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@DonRoth wrote:

I don't see these (Hough, Projection) options available in the other tools, like 'IMAQ Edge Tool 3', which is where I was looking originally.  Is a particular method used as default for this tool?

Also, is there a more complete discussion somewhere regarding using the hough transform for this purpose?

Thanks,

Don

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They are two different VIs. IMAQ Edge Tool 3 looking for single rising or falling edges along a defined path. Hough transforms is not useful for such task. IMAQ Find Edges finds straight edges. Hough algorithm is exactly intendend for searching straight edges (or arbitrary shapes like circles), therefore used in IMAQ Find Edges. In additional classical Hough trasform performed on binary images, so, I'm pretty sure, that inside of IMAQ Find Edges at the first IMAQ Edge Tool will be called, and then hough transform will be performed.