Error when calling MeshcatVisualizer.load_model_from_file() function

[LoreMoretti]

I am getting the following error when calling MeshcatVisualizer.load_model_from_file() function:

Using URDF model from: /home/lomoretti/mambaforge/envs/MeshcatVizBug/share/ergoCub/robots/ergoCubSN000/model.urdf
You can open the visualizer by visiting the following URL:
http://127.0.0.1:7000/static/
Traceback (most recent call last):
  File "<python-input-0>", line 20, in <module>
    visualizer.load_model_from_file(ergo_urdf_path, joint_names_list, robot_name)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/lomoretti/mambaforge/envs/MeshcatVizBug/lib/python3.13/site-packages/idyntree/visualize/meshcat_visualizer.py", line 609, in load_model_from_file
    ok = model_loader.loadReducedModelFromFile(path_str, considered_joints_idyn)
  File "/home/lomoretti/mambaforge/envs/MeshcatVizBug/lib/python3.13/site-packages/idyntree/swig.py", line 5694, in loadReducedModelFromFile
    return _iDynTree.ModelLoader_loadReducedModelFromFile(self, *args)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
TypeError: Wrong number or type of arguments for overloaded function 'ModelLoader_loadReducedModelFromFile'.
  Possible C/C++ prototypes are:
    iDynTree::ModelLoader::loadReducedModelFromFile(std::string const,std::vector< std::string,std::allocator< std::string > > const &,std::string const,std::vector< std::string,std::allocator< std::string > > const &)
    iDynTree::ModelLoader::loadReducedModelFromFile(std::string const,std::vector< std::string,std::allocator< std::string > > const &,std::string const)
    iDynTree::ModelLoader::loadReducedModelFromFile(std::string const,std::vector< std::string,std::allocator< std::string > > const &)
    iDynTree::ModelLoader::loadReducedModelFromFile(std::string const,std::vector< std::string,std::allocator< std::string > > const &,std::unordered_map< std::string,double,std::hash< std::string >,std::equal_to< std::string >,std::allocator< std::pair< std::string const,double > > > const &,std::string const,std::vector< std::string,std::allocator< std::string > > const &)
    iDynTree::ModelLoader::loadReducedModelFromFile(std::string const,std::vector< std::string,std::allocator< std::string > > const &,std::unordered_map< std::string,double,std::hash< std::string >,std::equal_to< std::string >,std::allocator< std::pair< std::string const,double > > > const &,std::string const)
    iDynTree::ModelLoader::loadReducedModelFromFile(std::string const,std::vector< std::string,std::allocator< std::string > > const &,std::unordered_map< std::string,double,std::hash< std::string >,std::equal_to< std::string >,std::allocator< std::pair< std::string const,double > > > const &)

Here the script which is throwing the error:

import os
import yarp
from idyntree.visualize import MeshcatVisualizer

network = yarp.Network()
os.environ["YARP_ROBOT_NAME"] = "ergoCubSN000"
ergo_urdf_path = yarp.ResourceFinder().findFileByName("model.urdf")
print("Using URDF model from:", ergo_urdf_path)
robot_name = "ergoCub"

joint_names_list = [
    "torso_pitch","torso_roll","torso_yaw",
    "l_shoulder_pitch","l_shoulder_roll","l_shoulder_yaw","l_elbow",
    "r_shoulder_pitch","r_shoulder_roll","r_shoulder_yaw","r_elbow",
    "l_hip_pitch","l_hip_roll","l_hip_yaw","l_knee","l_ankle_pitch","l_ankle_roll",
    "r_hip_pitch","r_hip_roll","r_hip_yaw","r_knee","r_ankle_pitch","r_ankle_roll",
]

visualizer = MeshcatVisualizer()
visualizer.load_model_from_file(ergo_urdf_path, joint_names_list, robot_name)

I have installed all dependencies in a conda environment:

conda install python ergocub-software yarp idyntree meshcat-python

[LoreMoretti]

The error is thrown at line 609:

https://github.com/robotology/idyntree/blob/69b81adaf2cd3eb46c0d500bfa1c623a4fb4cb7a/bindings/python/visualize/meshcat_visualizer.py#L605-L609

If I modify these lines as follow:

- considered_joints_idyn = idyn.StringVector()
- for joint in considered_joints:
-     considered_joints_idyn.push_back(joint)
-
- ok = model_loader.loadReducedModelFromFile(path_str, considered_joints_idyn)
+ ok = model_loader.loadReducedModelFromFile(path_str, considered_joints)

The model is loaded fine in the visualizer.

[LoreMoretti]

Here I found a unit test for the ModelLoader.loadReducedModelFromFile():

https://github.com/robotology/idyntree/blob/69b81adaf2cd3eb46c0d500bfa1c623a4fb4cb7a/bindings/python/tests/modelloader.py#L12-L18

In this unit test ModelLoader.loadReducedModelFromFile() is used in the same way as the modification I made above (i.e., use a list of standard python strings as considered_joints argument).

@traversaro can I open a PR with the above modification or am I missing something?

[traversaro]

Which version of iDynTree are you using? I guess this was a regression of #1255 . If using directly the Python list fixes your problem feel free to open a PR, but I would keep this issue (or open an new issue) to cover the StringVector usage.

[LoreMoretti]

Which version of iDynTree are you using?

The latest:

(MeshcatVizBug) ➜ ~ conda list | grep idyntree  
idyntree                  13.4.2          py313h7fcf629_2    conda-forge

[traversaro]

So it does not include #1255, so my assumption was wrong. Anyhow, feel free to open a PR to fix the issue, it does not make sense to couple this fix with other concerns.

[traversaro]

The master branch is a bit in a flux with a lot of changes for spherical joint support, so I prefer to wait for that to be finished (and bump major version) before a release, so once you do the fix I can backport it via a patch to the conda-forge feedstock.

[LoreMoretti]

More details follow.

The idyntree = 13.4.2 = py312h45012d9_0 conda-forge works fine (i.e. no issue in running the above example script).

While the idyntree = 13.4.2 = py312h6ea4fbf_2 conda-forge does not (not that I have downgraded python version wrt #1259 (comment) to try to determine what was causing the issue).

I have looked for packages info with conda search idyntree=13.4.2 --info:

idyntree 13.4.2 py312h45012d9_0
-------------------------------
file name   : idyntree-13.4.2-py312h45012d9_0.conda
name        : idyntree
version     : 13.4.2
build       : py312h45012d9_0
build number: 0
size        : 2.4 MB
license     : BSD-3-Clause
subdir      : linux-64
url         : https://conda.anaconda.org/conda-forge/linux-64/idyntree-13.4.2-py312h45012d9_0.conda
md5         : e8baad0a230e302544942c77b401bb57
timestamp   : 2025-06-10 14:23:55 UTC
dependencies: 
  - __glibc >=2.17,<3.0.a0
  - assimp >=5.4.3,<5.4.4.0a0
  - glfw >=3.4,<4.0a0
  - ipopt >=3.14.17,<3.14.18.0a0
  - irrlicht >=1.8.5,<1.9.0a0
  - libgcc >=13
  - libgl >=1.7.0,<2.0a0
  - libosqp >=1.0.0,<1.0.1.0a0
  - libstdcxx >=13
  - libxml2 >=2.13.8,<2.14.0a0
  - numpy >=1.23,<3
  - osqp-eigen >=0.10.1,<0.10.2.0a0
  - python >=3.12,<3.13.0a0
  - python_abi 3.12.* *_cp312
  - xorg-libx11 >=1.8.12,<2.0a0
  - xorg-libxfixes >=6.0.1,<7.0a0
  - xorg-libxrandr >=1.5.4,<2.0a0


idyntree 13.4.2 py312h6ea4fbf_1
-------------------------------
file name   : idyntree-13.4.2-py312h6ea4fbf_1.conda
name        : idyntree
version     : 13.4.2
build       : py312h6ea4fbf_1
build number: 1
size        : 2.4 MB
license     : BSD-3-Clause
subdir      : linux-64
url         : https://conda.anaconda.org/conda-forge/linux-64/idyntree-13.4.2-py312h6ea4fbf_1.conda
md5         : 9605931722a2f75b44722821f6e1d9e8
timestamp   : 2025-08-18 10:58:51 UTC
dependencies: 
  - __glibc >=2.17,<3.0.a0
  - assimp >=5.4.3,<5.4.4.0a0
  - glfw >=3.4.0,<4.0a0
  - ipopt >=3.14.19,<3.14.20.0a0
  - irrlicht >=1.8.5,<1.9.0a0
  - libgcc >=14
  - libgl >=1.7.0,<2.0a0
  - libosqp >=1.0.0,<1.0.1.0a0
  - libstdcxx >=14
  - libxml2 >=2.13.8,<2.14.0a0
  - numpy >=1.23,<3
  - osqp-eigen >=0.10.2,<0.10.3.0a0
  - python >=3.12,<3.13.0a0
  - python_abi 3.12.* *_cp312
  - xorg-libx11 >=1.8.12,<2.0a0
  - xorg-libxfixes >=6.0.1,<7.0a0
  - xorg-libxrandr >=1.5.4,<2.0a0


idyntree 13.4.2 py312h6ea4fbf_2
-------------------------------
file name   : idyntree-13.4.2-py312h6ea4fbf_2.conda
name        : idyntree
version     : 13.4.2
build       : py312h6ea4fbf_2
build number: 2
size        : 2.4 MB
license     : BSD-3-Clause
subdir      : linux-64
url         : https://conda.anaconda.org/conda-forge/linux-64/idyntree-13.4.2-py312h6ea4fbf_2.conda
md5         : f862af83e64e80d1ce0d46a9805b6bbc
timestamp   : 2025-08-30 07:08:58 UTC
dependencies: 
  - __glibc >=2.17,<3.0.a0
  - assimp >=5.4.3,<5.4.4.0a0
  - glfw >=3.4.0,<4.0a0
  - ipopt >=3.14.19,<3.14.20.0a0
  - irrlicht >=1.8.5,<1.9.0a0
  - libgcc >=14
  - libgl >=1.7.0,<2.0a0
  - libosqp >=1.0.0,<1.0.1.0a0
  - libstdcxx >=14
  - libxml2 >=2.13.8,<2.14.0a0
  - numpy >=1.23,<3
  - osqp-eigen >=0.10.3,<0.10.4.0a0
  - python >=3.12,<3.13.0a0
  - python_abi 3.12.* *_cp312
  - xorg-libx11 >=1.8.12,<2.0a0
  - xorg-libxfixes >=6.0.1,<7.0a0
  - xorg-libxrandr >=1.5.4,<2.0a0

Between builds py312h45012d9_0 (working) and py312h6ea4fbf_2 (not working) there is a third one py312h6ea4fbf_1, which I verified not to work as well.

Comparing py312h45012d9_0 (working) with py312h6ea4fbf_1 (not working), the dependencies which differ are:

py312h45012d9_0:

  - libgcc >=13
  - libstdcxx >=13
  - osqp-eigen >=0.10.1,<0.10.2.0a0

py312h6ea4fbf_1:

  - libgcc >=14
  - libstdcxx >=14
  - osqp-eigen >=0.10.2,<0.10.3.0a0

Now, excluding osqp-eigen which is not the source of problems here, could we blame more recent versions of libgcc and libstdcxx for the error? Maybe they are responsible of how types are passed from Python to C++.

[traversaro]

Good investigation! To provide more context, the _1 build was built from conda-forge/idyntree-feedstock@d7f0fc0 (see https://conda-metadata-app.streamlit.app/?q=conda-forge%2Flinux-64%2Fidyntree-13.4.2-py39h5b8d606_1.conda) while _0 from conda-forge/idyntree-feedstock@95d61be (see https://conda-metadata-app.streamlit.app/?q=conda-forge%2Flinux-64%2Fidyntree-13.4.2-py39h89e2db9_0.conda), so the diff is conda-forge/idyntree-feedstock@95d61be...d7f0fc0 .

[traversaro]

Anyhow, I think the "Error when calling MeshcatVisualizer.load_model_from_file() function" issue is fixed by the fix you propose, so let's fix it. The "StringVector overload are not working anymore with gcc 14" is probably much more complex, so we can probably just open a different issue.

[LoreMoretti]

The "StringVector overload are not working anymore with gcc 14" is probably much more complex, so we can probably just open a different issue.

Sure, here: #1260

[LoreMoretti]

Anyhow, I think the "Error when calling MeshcatVisualizer.load_model_from_file() function" issue is fixed by the fix you propose, so let's fix it.

PR: #1261

[traversaro]

Thanks @LoreMoretti ! I opened conda-forge/idyntree-feedstock#137 to fix the conda packages without the need to wait for a idyntree release (for which I would like to wait for #1258 to avoid bumping the major version for ABI changes multiple times in a short time).