How to find the curvature of the Points on the boundary

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harshal j 2015-12-2

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评论： Image Analyst 2021-8-17

Hi, I have obtain the object boundries by using the bwboundaries commond in MATLAB. Now I want to calculate the curvature of the point for example set of b(i-5), b(i), b(i+5). b(i) is the point on the boundary and b(i-5) & b(i+5) are the neighbors of the point. here b(i-5) and b(i+5) are end point of the set. Also i would like to find the distance of the point b(i) from the straight line connecting the two end points b(i-5) & b(i+5) of the set. I don't know how to obtain straight line between b(i-5) & b(i+5). Also i don't know how to calculate the perpendicular distance from the point b(i) with the straight ling joining b(i-5) & b(i+5). Please help me to solve this problem. Thanks in advance

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bilal zulfiqar 2021-8-17

在 MATLAB Online 中打开

Hello Harshal, 
Did you find the MATLAB code for this? I am also looking for the solution of similar problem. I want to first find the boundary coordinates and then finding the curvature for that. 
Would be nice if you can help in this regards,

Image Analyst 2021-8-17

@bilal zulfiqar for curvature, see

https://www.mathworks.com/matlabcentral/fileexchange/32696-2d-line-curvature-and-normals?s_tid=srchtitle

https://www.mathworks.com/matlabcentral/fileexchange/26706-active-shape-model-asm-and-active-appearance-model-aam?s_tid=srchtitle

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Torsten 2015-12-2

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http://mathworld.wolfram.com/Point-LineDistance3-Dimensional.html

Best wishes

Torsten.

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Torsten 2015-12-3

http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html

Best wishes

Torsten.

harshal j 2015-12-3

Thank u so much for the link. It will definitely solve my problem. Thanks once again..!

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Image Analyst 2015-12-2

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See Steve's presentation at ICIP http://blogs.mathworks.com/steve/files/MATLAB-Today-ICIP-2015-16x10-format-distribution-version-medium-quality-compression.pdf, and his discussion of alphaShape() and boundary(). Actually this should be a must read for everyone since it contains lots of good information on a wide variety of new functions.