Curve fitting in the cloud of pixels

[mihalis]

Hello,

I am not good at machine vision terminology, but I will try to express the problem.

I have cloud of pixels (on the picture) and I need to build a curve fitting of this cloud in the NI Vision Builder for AI (as formula or coefficients taking in the account density of the cloud). As I understand, I need an inspection step or the function kind of "Fitting Line" function or "Curve Fitting" function for the Vision Builder for AI. Do you have any Idea how to solve this problem ?

 Thank you!

[ChristopheC]

You probably want to use a Vision Assistant step. The vision function that performs the type of operation you describe is called a Skeleton.

I would first threshold the image, apply some morphology to create a single object out of the points, such as a close 9x9 or 11x11, then apply a skeleton in the advanced morphology step. The result has more branches that you show in your image.

Which version of VBAI are you using?

[mihalis]

Hello CristopheC,

thank you for the reply. Yes, you are right, I want to use Vision Assistant step for my application. I used the steps as you described, but in different order. You gave the right way how to use steps in correct order. But, I haven't  9x9 or 11x11 dot options, only 3x3, 5x5 and 7x7 available. What is wrong? I am using VBAI 2015.         

[GatorChomp]

Hi Mihalis,

While the full Vision Assistant software has the options CristopheC mentioned, when I looked in the VBAI 2015 Vision Assistant step these options were not possible. It looks like using that kernel size is not available in VBAI, and I'm not sure why there is a difference. You might be able to use several morphology steps or one of the Advanced Morphology steps to achieve the same effect. 

[mihalis]

Hi Charlie,

it's not a big problem about a kernel sizes, and as you mentioned, I use several morphology steps for achieve the effect. Thanks for the attention to the case.