# Interpolate Points of a 3D Point Cloud?

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newbie on 21 Feb 2020
Commented: Diego Hens on 25 Aug 2020
I am trying to interpolate data points (x, y, z) to get a point cloud with higher density.
I have triangulation points (x-y-z coordinates) and faces from a .stl-file (imported with stlread()) that I can work with. (DATA is attached).
In the attached image you can see the given data points (BLUE) and indicated the points I want to create (RED) - but for the whole geometry and in larger numbers.
Any ideas?
##### 2 CommentsShowHide 1 older comment
newbie on 21 Feb 2020
I´m sorry, attached as file.

darova on 21 Feb 2020
• Use griddata to create surface
• Use contour3 to create crossection
clc,clear
x = data(:,1);
y = data(:,2);
z = data(:,3);
[t,r] = cart2pol(x,y);
rr = linspace(min(r),max(r),20);
tt = linspace(0,2*pi,20);
[T,R] = meshgrid(tt,rr); % new mesh
[X,Y] = pol2cart(T,R); % convert new mesh to cartesian
Z = griddata(x,y,z,X,Y); % according Z coordinates
plot3(x,y,z,'.b')
hold on
surf(X,Y,Z,'faceColor','none','edgecolor',[1 1 1]*0.8)
contour3(X,Y,Z,[34 38])
hold off
axis equal
Result
##### 2 CommentsShowHide 1 older comment
Diego Hens on 25 Aug 2020
Thanks, this is going to be useful. I don't know how exactly, but it will :D

Daniel Vieira on 21 Feb 2020
try the scatteredInterpolant, should work fine with these points (not so much if you had a closed surface)
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Daniel Vieira on 26 Feb 2020
Actually it doesn't need any function, it does exactly the same thing as griddata (others posted solutions above using it). The difference is griddata creates the interpolation over the given points and that's it, while scatteredInterpolant creates a reusable interpolator for you to use in any points you want how many times you need.