Track the edge of a blob

Hello everyone!!.

I have the following problem, where I need to track these 2 blobs

the point is that it is an iterative and extremely variable problem.

SO

things like this could happen (when it could lose blob 1, losing a little but not all of its contour)

So I'm looking for a tracking method that doesn't rely on detecting specific objects.

If I could track edges that would be awesome.

Here is an example of 2 consecutive images

here is the view of the whole blob in its step 1 and 2

In other words, I only need to recognize when these 2 blobs (borders) are "inside" the large border.

specifically when the boundary between them is broken

if someone could give me some guidance it would be great!!!

Many thanks in advice!!!

Answer 1

[Image Analyst]

Look into bwboundaries() -- it will show you what boundaries are nested inside other boundaries. Or you can use inpolygon() to determine if a point is inside a polygon.

[KuroWings]

Hi, im just trying that, but... how do i track this case ?.

Frame 1

Frame 2

how do I track blob 2, because in that case bwboundaries() does not give the internal edges because it is broken.

With inpolygon(), is there any way to get all the inner edges of blob 2, assuming that I always get all the edges of blobs 1 and 2 in frame 1, then using inpolygon in frame 2, there is any way to get only the inner edge of blob 2?

to be more specific, I need to do this to find out all the time it takes for blob 1 and 2 to break their connection.

In any case, your answer is correct, thank you!!.

[Image Analyst]

If your boundaries are broken, you can try to connect them using imclose(). Your image is of very low resolution and imclose will change the shape a little bit (of course it has to if it's going to close that gap).

Otherwise you can look at more sophisticated techniques like "edge linking".

[KuroWings]

imclose won't work because that would close all the little blobs that are present in some cases, due to the variability of their shapes.

edge linking sounds good, I will check it out, Thank you very much!

Answer 2

[yanqi liu]

sir, the zip file contains 5 png file

what is the target? such as the right seperate?

[KuroWings]

Hi, the goal is to follow the inner line, even if it breaks, in order to track the blob.

the zip file is an example where in image 5, blobs 1 and 2 are separated, and i just need to recognize that without using a conventional object detector like vision.BlobAnalysis