ValueError: Can't clean for JSON: [0.0, 0.0, 8.508049964904785]

[Sapta0802]

I'm experiencing an issue when trying to preview an XML file from the Blender Mitsuba add-on in Google Colab using the Sionna library. The error message I receive is: ValueError: Can't clean for JSON: [0.0, 0.0, 8.508049964904785], Any guidance on how to resolve this.

[merlinND]

Hello @Sapta0802,

Does the scene render correctly with Mitsuba, not using Sionna? This will help check whether the problem comes from the scene or Sionna.
Please also share the scene file (including all meshes and textures) so that we can try reproducing locally.

[Sapta0802]

Thanks for your reply.

Mitsuba Rendering: I checked the scene by rendering it directly with Mitsuba, and it renders correctly.

Scene Files: I have uploaded the scene file, including all meshes and textures.
untitled_2.zip
meshes.zip

mainly this problem happens when I am using google colab.

[merlinND]

This is an issue from ipywidgets / traitlets which has already been fixed upstream (see e.g. jupyter-widgets/pythreejs#92).
The issue is that Google Colab seems to require a specific ipython and widgets version that does not include the fix. I tried selectively updating some packages, but couldn't find a combination that works.
Locally, everything works fine for me when using the latest ipython, jupyterlab and pythreejs versions.

I don't think there's anything we can do until Colab updates its ipython dependency.

[merlinND]

Edit: after searching on StackOverflow, I found a workaround for the IPython incompatibility, which allows updating IPython on your own in Colab.

Make the first cell of you Colab notebook the following:

!pip install ipython tornado ipywidgets traitlets --upgrade

# Source: https://stackoverflow.com/q/76837647
# There has got to be a better way to do this...but there's a bad import in some of the colab files
# IPython no longer exposes traitlets like this, it's a separate package now
!sed -i "s/from IPython.utils import traitlets as _traitlets/import traitlets as _traitlets/" /usr/local/lib/python3.10/dist-packages/google/colab/*.py
!sed -i "s/from IPython.utils import traitlets/import traitlets/" /usr/local/lib/python3.10/dist-packages/google/colab/*.py

!pip install sionna

Once it is done executing, restart the runtime and the scene preview should now work:

import sionna
scene = sionna.rt.load_scene('/content/scene/untitled_2.xml')
scene.preview()

[JNUshuaibi]

您好 ，

场景是否使用 Mitsuba 正确渲染，而不是使用 Sionna？这将有助于检查问题是来自 scene 还是 Sionna。请同时共享场景文件（包括所有网格和纹理），以便我们可以尝试在本地重现。

When I use Jupyter Notebook, I encountered this error. How should I resolve it?

[merlinND]

Hello @JNUshuaibi,

Did you try the solution described above in this thread?

If you're using a local Jupyter Notebook (not Colab), then the first thing to try would be to upgrade the relevant packages:

python3 -m pip install --upgrade jupyter jupyterlab ipython pythreejs ipywidgets traitlets