locate corners of polygon shape

[Alain_S]

Hi there,

I need to locate the middle point of the bended parts of the polygon shape.

Using the radius of x consecutive data points I can detect the straight parts of the polygon shape.
For each straight part in the shape there is one clear peak in the Radii graph.

That is all red dots on the polygone shape.

But for the bended parts of the shape 😞

I tried using the distance of each point toward the centre point but that doesn't work for all bended parts.

Question : Is there an algorithm that can detect the middle point of the bended parts of the polygon shape?

Thanks for any input

Best regards

Alain

[muks]

Can you post an image?

[Alain_S]

Yes, for sure 🙂

Setting for "Radii points" between 2 and 10

Setting for Peak Width: 4, not so important

Thanks for having a look at it !

Best regards

[johnsold]

Alain,

I have not had time to try this but here is a concept:

At the location of each of the Max Radii points extract a segment (+/-10 points?) of adjacent data points. For each segment fit a straight line. These lines will be approximately tangent to the flattest parts of the curve. The intersections of these lines are the vertexes of a polygon with the same number of sides as your data has Max Radii. The data point nearest the vertexes should be close to the corners.

Lynn

[Alain_S]

Hi Lynn,

Thanks for the methodology!

I'll give it a try on sevral shapes I have and come back to here... ...

Best Regards

Alain

[ghighuphu]

Lynn is right. If your "polygon" has symmetrically bended corners, the lagorithm detects the closest points and so the center f the bending.