Boundary function (Shrink Factor)

Hi, I worked on a project that required using the function [k,v]=boundary (x,y,z,s); where is s is the shrink factor that determines the tightness of the boundary enclosing the (x,y,z) data poits. I know what s does. But what's not mentioned in the MATLAB help to the best of my knowledge is , how does s work? I need to know the answer to that for two reasons. 1- it may help me choose the best s for my application. 2- I need to know if there is an explanation to how it works so I can put it in my project report!!!

If you have an idea about this, please do share! it's really important and kind of urgent too :)

Thanks, Amin

Answer 1

[Walter Roberson]

You can read the code for boundary(). It creates an alpha shape object with the vertices and infinite alpha. It then uses the alphaSpectrum() method on the alpha shape object:

"a = alphaSpectrum(shp) returns the values of the alpha radius that produce distinct alpha shapes. a is in descending sorted order. Each element in a represents a value of the alpha radius that results in a distinct shape."

It then goes 1-S of the way through the list and uses that alpha.

[Amin Kassab-Bachi]

Thanks a lot! that's really helpful.