How to Plot the smooth envelope of 3D scattered points

For example, in this 3D scatter plot, how do I draw an envelope so that all the points are inside the surface?Thx!!!!!!!!

Answer 1

[Bjorn Gustavsson]

You will get the tightest surface enclosing all points with the convhulln function. That will not be a smooth surface since it is composed of triangles between your points on a convex surface enclosing all the points. You might get a smoother surface using alpha-shape techniques, perhaps this FEX-submission: fast-alpha-hulls-alpha-shapes-in-3d-parfor-enabled.

HTH

[Rex Chiu]

Thank you for your answer, I will go try this method you mentioned!

[Rex Chiu]

hey bro,i use alphaShape() to plot my points,but the result is sad.

[KSSV]

Aattach your data.

[Rex Chiu]

Here's my data,thank u.

[Bjorn Gustavsson]

@Rex Chiu: To my understanding of alpha-shapes the idea is that one sould be able to control how sharp curvature the surface would have by adjusting the alpha-parameter. If this tool doesn't work, maybe some of the other alpha-shape submissions on the file-exchange will.

[Rex Chiu]

Ah.i cannot found a good way,so far.

Answer 2

[KSSV]

Read about griddata and/or scatteredInterpolant.

[Rex Chiu]

Thank you for your answer, its useful for me.

Answer 3

[Star Strider]

See if the boundary function offers an improvement.

[Rex Chiu]

Hi Star Strider!I have to say that the graph plotted with the boundary function, the graph boundary is too sharp and not smooth enough. However, thanks for your answer!

[Star Strider]

My pleasure!

I do not know how you coded that.

See the documentation section on Shrink Factor Effect on 3-D Boundary to see if a larger shrink factor could improve the result.

[Rex Chiu]

re Star Strider:

im afraid not that larger shrink factor can improve the result.

i choose 1 as the shrink factor this is the result.

[Star Strider]

O.K. That was my best shot!

I will explore another idea I have, and if it works, I will post it here. (It could take at least a few hours.) If it does not, I will delete my Answer here.

[Rex Chiu]

O.K. i hope to ur great idea!