Point cloud to Mesh/Surface/Grid to STL

I have a data set of (x,y,z) coordinates for several points that form a point cloud in the form of the bones in a human leg. I want to use nearest neighbor interpolation of these points in order to create a grid and eventually an stl file to export to solid works. Thanks

[Zara]

To create an STL file from your point cloud data of a human leg's bones, follow these

1. Preprocess the Point Cloud

• Ensure your dataset is clean and well-distributed.
• Remove noise and outliers if needed.

2. Create a Grid Using Nearest Neighbor Interpolation

Since your data is a scattered point cloud, you can use nearest neighbor interpolation to resample it onto a structured grid. This can be done using SciPy’s griddata or sklearn.neighbors.KNeighborsRegressor.

Example using scipy.interpolate.griddata:

import numpy as np

import scipy.interpolate as interp

# Load your point cloud (x, y, z)

points = np.loadtxt("point_cloud.txt") # Assuming x, y, z columns

x, y, z = points[:, 0], points[:, 1], points[:, 2]

# Define grid resolution

grid_x, grid_y = np.meshgrid(np.linspace(min(x), max(x), 100),

np.linspace(min(y), max(y), 100))

# Interpolate z values using nearest neighbor

grid_z = interp.griddata((x, y), z, (grid_x, grid_y), method='nearest')

3. Generate a Mesh from the Grid

• Convert the interpolated grid into a mesh.
• Use matplotlib.tri or scipy.spatial.Delaunay for triangulation.

Example using Delaunay:

from scipy.spatial import Delaunay

points2D = np.vstack((x, y)).T

tri = Delaunay(points2D)

4. Export to STL Format

Use trimesh or meshio to export the triangulated mesh into an STL file.

Example using trimesh:

import trimesh

mesh = trimesh.Trimesh(vertices=points, faces=tri.simplices)

mesh.export("bone_mesh.stl")

5. Open in SolidWorks

• Import the bone_mesh.stl file into SolidWorks.
• Use the "Mesh to BREP" function to convert it into a solid body.

Alternative Approach

If you need a smoother surface, consider using Poisson surface reconstruction (open3d.geometry.TriangleMesh.create_from_point_cloud_poisson).

To know fore more details

https://marsbiminternational.com/bim/scan-to-bim.html

Answer 1

[Caleb Williams]

Five years later, but may still be relevant...

Try using the "boundary" function. You can input a point cloud of (x,y,z) coordinates and it will return the solid formed by them. You can graph it using "trisurf."

Hope this helps!

[Sathish Balakrishnan]

3 years after your answer, it helped me, ha ha :)

[Veronica Taurino]

let's say 4 years later, also! Thank you

[Andrés Morales]

And some days later, Thank you too!

[Karam Elabd]

Gratitude from 2022! this comment worked for me too :)

[Ankit]

Wow thats great!

[Zhaowei Liu]

It still works in 2024!

[志乾]

still works until December 2024 !

here's my code:

points = [X,Y,Z];

points = unique(points,"rows");

T = boundary(points(:,1),points(:,2), points(:,3));

tri = triangulation(T,points(:,1),points(:,2), points(:,3));

stlwrite(tri,'output.stl');

trisurf(T,points(:,1),points(:,2), points(:,3));

Answer 2

[Andrew]

You could check out this: http://iso2mesh.sourceforge.net/cgi-bin/index.cgi

... it has lots of tools for creating meshes from various types of data.

Answer 3

[KSSV]

Check the following file in mathworks file exchange...It will convert the mesh to stl file, which you can export to other wares..

http://www.mathworks.in/matlabcentral/fileexchange/4512-surf2stl

Sreenu

[Isabella]

i need a way to convert the point cloud to a mesh. That is the step i am hung up on. There is also a function in the file exchange that converts surfaces to stl so i need to convert my point cloud to these forms first.

Answer 4

[Walter Roberson]

I suggest you look in the FEX for John D'Errico's work on Alpha Shapes.

[Isabella]

Could you post a link to the specific file you are referring to? Thank you

[Walter Roberson]

Darn, I get confused sometimes about what John has released or not. He has spoken of his code in the past, but it looks like he has not put it on the FEX.

Answer 5

[Anil Kamat]

You can also do it using tri and trimesh function:

example:

DefoNodes--> x,y and z coordinates of each Node

tri = delaunay(DefoNodes(1,:),DefoNodes(2,:));
trimesh(tri, DefoNodes(1,:), DefoNodes(2,:), DefoNodes(3,:),'EdgeColor','k');

Answer 6

[mars bim]

Hi, Great writing! I have a question about using PointCab Suite. I read introduction of Point cloud to BIM on an article https://www.marsbim.com/blog/scan-to-bim-introduction-from-technology-to-the-bim-model/ and understand about PointCab Suite Revit. And I know that PointCab Suite is powerfull tool for point cloud modeling and easily manage .LAS files and covert it into .RCP format. But when to load that file in Revit, I received some issue on that process. Is there any other format to directly open point cloud files in to Revit? Thanks.