Meshlab script works from Python venv, but not after pyinstaller

Question

I have a simple Python script Mesher.py which takes file name strings in Windows format on the command line and runs MeshLab on the input point cloud (.xyz file):

import sys
from pathlib import Path
import pymeshlab as ml

xyz_file = Path(sys.argv[1]).as_posix()
output_file = Path(sys.argv[2]).as_posix()

ms = ml.MeshSet()
ms.load_new_mesh(xyz_file)
ms.load_filter_script('filters.mlx')
ms.apply_filter_script()
ms.save_current_mesh(output_file)

It runs fine from the Python 3.9.6 interpreter in a virtual environment, but when I package it with pyinstaller (also installed to the venv) to make a Windows executable out of it I get this error when I run the .exe with the same command line arguments:

    Traceback (most recent call last):
      File "Mesher.py", line 9, in <module>
        ms.load_new_mesh(xyz_file)
    pymeshlab.pmeshlab.PyMeshLabException: Unknown format for load: xyz
    [24580] Failed to execute script Mesher

Why does pymeshlab recognize my .xyz file fine from Python but not when the same script is wrapped up in a Windows executable?

EDIT This also happens when I use a fixed file name for my .xyz file rather than passing it on the command line, or even if I use a .ply file for the input. The .exe version of my script doesn't recognize standard MeshLab file types.

Answer 1

I was able to get this to work by using cx_Freeze instead of pyinstaller.