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Voxelization Workshop

In this workshop we will learn how to voxelize a geometry and construct a lattice from it.

0. Initialization

Importing all necessary libraries and specifying the inputs

# !conda env update -f ../environment.yml

import os
import topogenesis as tg
import trimesh as tm
import numpy as np
import pyvista as pv
#pv.set_jupyter_backend("ipyvtklink")

vs = 1.4
vh = 3.2

unit = [vs, vs, vh]
mesh_path = os.path.relpath('../data/meshes/compulsory_envelope.obj')

1. Input Mesh

# load the mesh from file
mesh = tm.load(mesh_path)
# Check if the mesh is watertight
print(mesh.is_watertight)

# convert trimesh to pv_mesh
def tri_to_pv(tri_mesh):
    faces = np.pad(tri_mesh.faces, ((0, 0),(1,0)), 'constant', constant_values=3)
    pv_mesh = pv.PolyData(tri_mesh.vertices, faces)
    return pv_mesh

# Visualize the mesh using pyvista plotter
#######

# initiating the plotter
p = pv.Plotter()

# adding the base mesh: light blue
p.add_mesh(tri_to_pv(mesh), color='#abd8ff')

#plotting
cpos = [(314.348192231551, 283.381630231551, 296.74455709155103),
 (65.08283250000001, -12.333572500000002, 21.07374465),
 (0.0, 0.0, 1.0)]
p.camera_position = cpos
p.window_size = 2000, 1000
p.show(use_ipyvtk=True)
p.screenshot("../data/images/voxelization_highres1")
print(p.camera_position)

2. Voxelize the Mesh

# initialize the base lattice
base_lattice = tg.lattice(mesh.bounds, unit=unit, default_value=1, dtype=int)

# check which voxel centroids is inside the mesh
interior_condition = mesh.contains(base_lattice.centroids)

# reshape the interior condition to the shape of the base_lattice
interior_array = interior_condition.reshape(base_lattice.shape)

# convert the interior array into a lattice
interior_lattice = tg.to_lattice(interior_array, base_lattice.minbound, base_lattice.unit)

2.1 Visualizing Highres lattice

# convert trimesh to pv_mesh
def tri_to_pv(tri_mesh):
    faces = np.pad(tri_mesh.faces, ((0, 0),(1,0)), 'constant', constant_values=3)
    pv_mesh = pv.PolyData(tri_mesh.vertices, faces)
    return pv_mesh

# Visualize the voxelization using pyvista plotter
#####

# initiating the plotter
p = pv.Plotter()

# fast visualization of the lattice
interior_lattice.fast_vis(p)

# adding the base mesh: light blue
p.add_mesh(tri_to_pv(mesh), color='#abd8ff', opacity=0.1)

#plotting
cpos = [(314.348192231551, 283.381630231551, 296.74455709155103),
 (65.08283250000001, -12.333572500000002, 21.07374465),
 (0.0, 0.0, 1.0)]
p.camera_position = cpos
p.window_size = 2000, 1000
p.show(use_ipyvtk=True)
p.screenshot("../data/images/voxelization_highres2")
print(p.camera_position)

2.2 Lattice Dimensions

interior_lattice.shape

3. Saving the lattice to CSV

csv_path = os.path.relpath('../data/meshes/voxelized_envelope_highres.csv')
interior_lattice.to_csv(csv_path)

Credits

__author__ = "Shervin Azadi"
__license__ = "MIT"
__version__ = "1.0"
__url__ = "https://github.com/shervinazadi/spatial_computing_workshops"
__summary__ = "Spatial Computing Design Studio Workshop on Voxelization"