Negative volume on importing stl mesh

[parmodhattri]

1. On importing stl mesh file I get negative volume for it. Can someone help me in figuring out why?
2. I have created triangular mesh for a cube of 5m side.

from stl import mesh the_mesh = mesh.Mesh.from_file(filename="cube5m_reshuffled.stl") volume, COG, inertia_matrix=the_mesh.get_mass_properties() print('volume is', volume)

[fakufaku]

Hi @parmodhattri , the volume computation routine (and pyroomacoustics in general) assumes that the surface normals are all pointing outward from the room. Also there should be no holes in the mesh.

[parmodhattri]

""" Hi @fakufaku thanks for the response. Yes, surface normals are pointing outwards but don't have any holes in the mesh. And when I create room with this mesh for ray tracing (as shown below), it computes -ve no of rays for ray tracing (in room.rt_args). Can you help me in solving this?

"""

code

from stl import mesh import pyroomacoustics as pra import numpy as np the_mesh = mesh.Mesh.from_file(filename="cube5m_reshuffled.stl") volume, COG, inertia_matrix=the_mesh.get_mass_properties()

Create one wall per triangle

walls = [] for w in range(ntriang): walls.append( pra.wall_factory( np.array(the_mesh.vectors[w].T / size_reduc_factor), material.energy_absorption["coeffs"], material.scattering["coeffs"], ) )

Creating room from mesh

room = ( pra.Room( walls, fs=16000, max_order=1, ray_tracing=True, air_absorption=True) .add_source(np.array([2.5, 2.5, 2.5]).reshape(3,1),signal=signal) .add_microphone_array(np.c_[np.array([2.2, 2.2, 2.5])]) )

To check the arguments for ray tracing.

room.rt_args

[fakufaku]

Can you please provide the STL file ?