"ZeroDivisionError: float division by zero" when using Parameterized Tesselated Geometry

Physics Simulation PhysicsNeMo-ML Model Framework Technical Support (PhysicsNeMo Only)
1

Hello,

I want to make a parameterized discrete geometry out of tesselated geometries. When I execute the code I get a strange error:

/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/tessellation.py:104: RuntimeWarning: divide by zero encountered in true_divide
  np.full(x.shape, triangle_areas[index] / x.shape[0])
Traceback (most recent call last):
  File "heatsink/heatsink_design/heatsink_debug.py", line 97, in <module>
    main()
  File "heatsink/heatsink_design/heatsink_debug.py", line 28, in wrapper
    result = func(*args, **kwargs)
  File "heatsink/heatsink_design/heatsink_debug.py", line 91, in main
    s1 = (no_slip).sample_boundary(nr_points=nr_points)
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/geometry.py", line 488, in sample_boundary
    [
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/geometry.py", line 489, in <listcomp>
    curve.approx_area(parameterization, criteria=closed_boundary_criteria)
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/curve.py", line 148, in approx_area
    computed_criteria = criteria(s, p)
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/geometry.py", line 480, in boundary_criteria
    return self.boundary_criteria(invar, criteria=criteria, params=params)
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/geometry.py", line 401, in boundary_criteria
    sdf_normal_plus = self.sdf(
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/discrete_geometry.py", line 73, in sdf
    computed_sdf = f(
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/geometry.py", line 111, in scale_sdf
    computed_sdf = sdf(scaled_invar, params, compute_sdf_derivatives)
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/geometry.py", line 189, in translate_sdf
    computed_sdf = sdf(translated_invar, params, compute_sdf_derivatives)
  File "/usr/local/lib/python3.8/dist-packages/modulus/sym/geometry/tessellation.py", line 135, in sdf
    store_triangles *= 1 / max_dis
ZeroDivisionError: float division by zero

This error occures only when I try to make a discrete geometry out of tesselated geometries, I can sample points on each tesselated geometry that I use without any problem. Here is a code that produces an error:

# import Modulus library
import os
import psutil

from sympy import Symbol, Eq, tanh, Max
import numpy as np
import itertools
import os
import pandas as pd
from modulus.sym.geometry import Parameterization, Parameter
from modulus.sym.geometry.discrete_geometry import DiscreteGeometry
from modulus.sym.utils.io.vtk import var_to_polyvtk
from modulus.sym.geometry.tessellation import Tessellation
from modulus.sym.hydra import to_absolute_path


def parse_file(filename, airtight: bool = False):
    geo = Tessellation.from_stl(
        "/root/workspace/heatsink/stl_files/" + filename, airtight=airtight
        )    
    geo_translated = geo.translate([0., -0.0261136, -0.02494])
    return geo_translated

alpha = Symbol("alpha")
hc = Symbol("hc")
he = Symbol("he")

fixed_param_ranges = {
    alpha: 1.72,
    hc: 19.72,
    he: 12.78,
}

noslip_geos = []
interior_geos = []

for n in range(1, 20):
    noslip_geos.append(parse_file("Design_"+str(n)+"/no_slip.stl", False))
    interior_geos.append(parse_file("Design_"+str(n)+"/interior.stl", True))
    

df = pd.read_csv("/root/workspace/heatsink/stl_files/DOE_Plan_OLH_Distribution.csv", sep="\t", header=0)
alpha_par = df.iloc[:, 1].values.copy()
hc_par = df.iloc[:, 2].values.copy()
he_par = df.iloc[:, 3].values.copy()

par = Parameterization(
    {
        Parameter("alpha"): alpha_par[:, None],
        Parameter("he"): he_par[:, None],
        Parameter("hc"): hc_par[:, None],
    }
)

no_slip = DiscreteGeometry(noslip_geos, par)
interior = DiscreteGeometry(interior_geos, par)

nr_points = 100
s1 = (no_slip).sample_boundary(nr_points=nr_points)
print(s1)
s1 = (interior).sample_interior(nr_points=nr_points, compute_sdf_derivatives=True)
print(s1)

I would be great if you could help me resolve this issue.

Thank you

2

Hi @gorpinich4

This typically happens when the geometry module samples 0 points (somethings up with the sampling bounds, geometry itself, etc). Does a single tessellated geometry from the parse_file sample alright?

E.g.

geo = parse_file("Design_1/no_slip.stl", False)
s = geo.sample_interior(nr_points=100, compute_sdf_derivatives=True)
var_to_polyvtk(s, "interior")
3

Yes, I tried to sample on all geometries separately and everything works well