Remeshing an stl

OpenSCAD, like most CAD programs, does not generate nice surface meshes for use in CFD. The surface mesh is often very coarse and not isotropic. This can lead to poor quality simulations. To improve the mesh quality, we can use the pyMeshLab package to remesh the stl file.

Here, we demonstrate a pyMeshLab wrapper function that can be used to remesh the stl file.

This script demonstrates the remeshing of an STL file using the vSCAD library.

Importing the OpenSCAD-generated STL file

First, we import the OpenSCAD-generated STL file that we want to remesh. We pass the path to the STL file to the Remesh class.

import vSCAD as vs

stl_path = 'scad-stl/vessel.stl'

remesh = vs.Remesh(stl_path)

Adjusting the remeshing parameters

Next, we set the remeshing parameters. We first set the coursest isotropic cell diameter to use:

remesh.set_initial_target_length_percentage(0.6)

This sets the initial target length as a percentage (0.6%) of the bounding box diagonal.

We also set the final target length:

remesh.set_final_target_length_percentage(0.1)

We will then set the target length reduction step size: Here we set it to 0.1% of the bounding box diagonal.

remesh.set_target_length_reduction_step_size(0.1)

This will recursively remesh the geometry until the target length is reached.

We can additionally set the number of isotropic remeshing iterations and smoothing iterations for each recursive remeshing step:

remesh.set_isotropic_remeshing_iterations(3)
remesh.set_recursive_smoothing_iterations(10)

Finally, we set the final smoothing iterations:

remesh.set_final_smoothing_iterations(10)

We also can save the mesh at a specified interval during the remeshing process.

remesh.set_saveout_period(10)

Finally, with these parameters set, we can perform the remeshing process and save the final STL file:

remesh.remesh_stl()

The full script is shown below:

import vSCAD as vs

stl_path = 'scad-stl/vessel.stl'

remesh = vs.Remesh(stl_path)

remesh.set_initial_target_length_percentage(0.6)
remesh.set_final_target_length_percentage(0.1)
remesh.set_target_length_reduction_step_size(0.1)
remesh.set_isotropic_remeshing_iterations(3)
remesh.set_recursive_smoothing_iterations(10)
remesh.set_final_smoothing_iterations(10)
remesh.set_saveout_period(10)

remesh.remesh_stl()

The full script

import vSCAD as vs

# Path to the OpenSCAD-generated STL file
stl_path = 'scad-stl/vessel.stl'

# Create a Remesh object
remesh = vs.Remesh(stl_path)

# Set remeshing parameters
remesh.set_initial_target_length_percentage(0.6)
remesh.set_final_target_length_percentage(0.1)
remesh.set_target_length_reduction_step_size(0.1)
remesh.set_isotropic_remeshing_iterations(3)
remesh.set_recursive_smoothing_iterations(10)
remesh.set_final_smoothing_iterations(10)
remesh.set_saveout_period(10)

# Perform the remeshing process
remesh.remesh_stl()