How to get a region chain code?

[Stéfan van der Walt]

This is the third time in about a month that we have the need to determine
geometric properties of regions. The right solution here is to build a
region graph, like I described in the ticket (sorry, I can't check the
number from my phone right now). Would anyone be interested in helping to
implement that?

In the meantime we can implement the border finding manually, and later
just slot in the new structure.

Stéfan
On 16 Jul 2013 07:03, "Chintak Sheth" <chintaksheth at gmail.com> wrote:

> Hi Valeriy,
>
> Wow a compression technique! That would surely be a great addition.
>
> > I am studying a shape descriptors and would like to compute a chain code
> description of a labeled shape. I was trying to look into docs but have not
> find a direct way to get this region property with skimage. Is there any
> way to do it in a few calls which I missed?
> >
>
> - Extract the boundary. `skimage.morphology.erosion` using
> `skimage.morphology.disk` structuring element with radius 1. Then subtract
> this from the original image.
>
> - Label the boundaries. If you already have a labeled image, then that
> saves you a function call else there is `label` function in
> `skimage.morphology`.
>
> - Use `np.transpose(np.where(label == 1))` to generate the indices of
> pixels marked as label 1. This will return a `list` of indices. You can
> simply use the first as the starting point.
>
> This should help set up the stage for the traversal. Hope this helps a bit.
>
> Chintak.
>
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