# 3D plotted shape is not following curvature of data points

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Sumeet Chaudhari on 6 Jul 2020
Edited: John D'Errico on 6 Jul 2020
I am writing a code that creates a 3D shape from a set of data points and am running into this problem where the shape does not properly follow the curvature of the data points and rather draws a straight line. This can be seen on the sides of the figure below where the shape isn't properly following the data points into the curves.
My code:
x = seg_info(:, 1);
y = seg_info(:, 2);
z = seg_info(:, 3);
colors = seg_info(:, 4);
scatter3(x,y,z);
hold on;
DT = delaunayTriangulation(x, y, z);
[K, v] = convexHull(DT);
trisurf(K, DT.Points(:,1), DT.Points(:,2), DT.Points(:,3), ...
'FaceAlpha', 0.5, 'EdgeColor', 'none', ...
'CData', colors, 'FaceColor', 'interp');
Does anyone know how I can improve my code to better fit these sides? I have tried using alpha shapes and boundary in an attempt to derive the concave hull but neither worked.
Sumeet Chaudhari on 6 Jul 2020
I have been trying to use mesh and even searching File Exchange for a program that calculates a concave hull. Looking at a scatter3 plot, I wish there was a way to just connect all the dots since the input data already represents the outer surface of the shape.

jonas on 6 Jul 2020
##### 2 CommentsShowHide 1 older comment
John D'Errico on 6 Jul 2020
Edited: John D'Errico on 6 Jul 2020
Assuming that is a CRUST implementation, it is probably the best choice. And a quick glance at the code suggests it is indeed CRUST.
An alternative code can be found here:

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