How to reuse my scenes in the new Sionna v1.0.2

[Mohkared]

Hi all,

First off, I’d like to extend a huge thank you to the developers for the incredible updates in Sionna v1.0.2! The improvements and enhancements are greatly appreciated.

I recently upgraded to the latest version, but I’ve encountered an issue—scenes that I created and used in the previous version (Sionna v0.19.1) no longer work in the newer version (Sionna v1.0.2).

I have tried to follow the new documentation, but this issue was not mentioned. Could you please provide guidance on how to resolve this? Are there any required modifications or compatibility steps that I need to follow?

This is the error in (Sionna v1.0.2):

RuntimeError                              Traceback (most recent call last)
Cell In[19], line 1
----> 1 scene = load_scene(main_path+'\\scene_v2_5.xml')
      2 scene.frequency = 28e9

File path-to-venv\.venv\Lib\site-packages\sionna\rt\scene.py:1041, in load_scene(filename, merge_shapes, merge_shapes_exclude_regex)
   1039 try:
   1040     thread.set_file_resolver(fres)
-> 1041     mi_scene = mi.load_string(processed)
   1042 finally:
   1043     thread.set_file_resolver(fres_old)

RuntimeError: ​[xml.cpp:1082] Error while loading "<string>" (near line 12, col 10): could not instantiate bsdf plugin of type "itu-radio-material": Traceback (most recent call last):
[xml.cpp:1082]   File "path-to-venv\.venv\Lib\site-packages\sionna\rt\radio_materials\itu_material.py", line 142, in <lambda>
[xml.cpp:1082]   File "path-to-venv\.venv\Lib\site-packages\sionna\rt\radio_materials\itu_material.py", line 92, in __init__
[xml.cpp:1082] ValueError: Invalid ITU material type

This is a sample of the exported scene .xml:

<scene version="2.1.0">

<!-- Defaults, these can be set via the command line: -Darg=value -->


<!-- Camera and Rendering Parameters -->

	<integrator type="path" id="elm__0" name="elm__0">
		<integer name="max_depth" value="12"/>
	</integrator>

<!-- Materials -->

	<bsdf type="twosided" id="mat-itu_concrete" name="mat-itu_concrete">
		<bsdf type="principled" name="bsdf">
			<rgb value="0.800000 0.800000 0.800000" name="base_color"/>
			<rgb value="1.000000 1.000000 1.000000" name="spec_tint"/>
			<float name="spec_trans" value="0.000000"/>
			<float name="metallic" value="0.000000"/>
			<float name="anisotropic" value="0.000000"/>
			<float name="roughness" value="0.250000"/>
			<float name="sheen" value="0.000000"/>
			<rgb value="1.000000 1.000000 1.000000" name="sheen_tint"/>
			<float name="clearcoat" value="0.000000"/>
			<float name="clearcoat_gloss" value="0.000900"/>
			<float name="specular" value="0.500000"/>
		</bsdf>
	</bsdf>
	<bsdf type="twosided" id="mat-itu_human" name="mat-itu_human">
		<bsdf type="principled" name="bsdf">
			<rgb value="0.733221 0.800047 0.005877" name="base_color"/>
			<rgb value="1.000000 1.000000 1.000000" name="spec_tint"/>
			<float name="spec_trans" value="0.000000"/>
			<float name="metallic" value="0.000000"/>
			<float name="anisotropic" value="0.000000"/>
			<float name="roughness" value="0.250000"/>
			<float name="sheen" value="0.000000"/>
			<rgb value="1.000000 1.000000 1.000000" name="sheen_tint"/>
			<float name="clearcoat" value="0.000000"/>
			<float name="clearcoat_gloss" value="0.000900"/>
			<float name="specular" value="0.500000"/>
		</bsdf>
	</bsdf>
	<bsdf type="twosided" id="mat-itu_metal" name="mat-itu_metal">
		<bsdf type="principled" name="bsdf">
			<rgb value="0.076512 0.066013 0.059846" name="base_color"/>
			<rgb value="1.000000 1.000000 1.000000" name="spec_tint"/>
			<float name="spec_trans" value="0.000000"/>
			<float name="metallic" value="0.652582"/>
			<float name="anisotropic" value="0.000000"/>
			<float name="roughness" value="0.611039"/>
			<float name="sheen" value="0.000000"/>
			<rgb value="1.000000 1.000000 1.000000" name="sheen_tint"/>
			<float name="clearcoat" value="0.000000"/>
			<float name="clearcoat_gloss" value="0.000900"/>
			<float name="specular" value="0.500000"/>
		</bsdf>
	</bsdf>

<!-- Emitters -->

	<emitter type="constant" id="World" name="World">
		<rgb value="0.776519 0.776519 0.776519" name="radiance"/>
	</emitter>

<!-- Shapes -->

	<shape type="ply" id="mesh-Plane" name="mesh-Plane">
		<string name="filename" value="meshes/Plane.ply"/>
		<boolean name="face_normals" value="true"/>
		<ref id="mat-itu_concrete" name="bsdf"/>
	</shape>
	<shape type="ply" id="mesh-human_001" name="mesh-human_001">
		<string name="filename" value="meshes/human_001.ply"/>
		<boolean name="face_normals" value="true"/>
		<ref id="mat-itu_human" name="bsdf"/>
	</shape>
	<shape type="ply" id="mesh-human_001_001" name="mesh-human_001_001">
		<string name="filename" value="meshes/human_001_001.ply"/>
		<boolean name="face_normals" value="true"/>
		<ref id="mat-itu_human" name="bsdf"/>
	</shape>
	<shape type="ply" id="mesh-Cylinder" name="mesh-Cylinder">
		<string name="filename" value="meshes/Cylinder.ply"/>
		<boolean name="face_normals" value="true"/>
		<ref id="mat-itu_metal" name="bsdf"/>
	</shape>

Also, I was wondering if there is a chance to post a tutorial for the latest updates.

Looking forward to your insights. Thanks in advance for your help!

[merlinND]

Hello @Mohkared,

Your scene uses a material name mat-itu_human, but this material is not defined in the built-in Sionna ITURadioMaterial:
https://github.com/NVlabs/sionna-rt/blob/f3a944cbb7b4945975fad21353413b3b7c8a477e/src/sionna/rt/radio_materials/itu_material.py#L55-L68

This is detected and results in the error that you encountered.

[Mohkared]

Hi @merlinND,

Thanks, that was indeed the issue. Interestingly, it worked fine in the previous version (Sionna v0.19.1).
What I have changed is the .xml file: I removed the mat-itu_human and for the objects that used that material, I have assigned mat-itu_concrete as a default. That seemed to work.

However, when I try to access those objects and assign them my custom radio material, it returns None
I tried to follow the documentation, but it gives the same result.

Do you know what might have caused this?

The following code is a demonstration:
Code 1:

scene1 = load_scene('scenes/scene_v2_5.xml')
for obj in scene1.objects.values():
    print(obj.name)

Output: Sionna v0.19.1

Cylinder
Cylinder_001
Cylinder_002
...
Cylinder_068
Plane
human_001
human_001_001

Output: Sionna v1.0.2

no-name-1
no-name-2

Code 2:

print(scene1.get('human_001_001'))

Output: Sionna v0.19.1

<sionna.rt.scene_object.SceneObject object at 0x000002A5859E3050>

Output: Sionna v1.0.2

None

Code 3:

scene2 = load_scene(sionna.rt.scene.munich)
for obj in scene2.objects.values():
    print(obj.name)

Output: Sionna v0.19.1

Heilig_Geist-itu_marble
Heilig_Geist-itu_metal
Altes_Rathaus-itu_marble
Altes_Rathaus-itu_metal
Schrannenhalle-itu_marble
Schrannenhalle-itu_metal
element_001-itu_marble
element_001-itu_metal
Bayerisches_Nationaltheater-itu_marble
Bayerisches_Nationaltheater-itu_metal
Hofbr_uhaus-itu_marble
Hofbr_uhaus-itu_metal
Ohel_Jakob_Hauptsynagoge-itu_marble
Ohel_Jakob_Hauptsynagoge-itu_metal
J_disches_Museum-itu_marble
J_disches_Museum-itu_metal
Israelitische_Kultusgemeinde__Gemeindezentrum_-itu_marble
Israelitische_Kultusgemeinde__Gemeindezentrum_-itu_metal
Max-Planck-Gesellschaft-itu_marble
Max-Planck-Gesellschaft-itu_metal
MMC-itu_marble
MMC-itu_metal
Bayerisches_Staatsschauspiel_-_Marstall-itu_marble
Bayerisches_Staatsschauspiel_-_Marstall-itu_metal
element_003-itu_marble
...
Palais_Toerring-Jettenbach-itu_marble
element_1364-itu_metal
element_1364-itu_marble
ground

Output: Sionna v1.0.2

Heilig_Geist-itu_marble
Heilig_Geist-itu_metal
Frauenkirche-itu_marble
Frauenkirche-itu_metal
St__Peter-itu_marble
St__Peter-itu_metal
no-name-3
no-name-4
no-name-5
no-name-6
ground

Code 4:

print(scene2.get('Schrannenhalle-itu_metal'))

Output: Sionna v0.19.1

<sionna.rt.scene_object.SceneObject object at 0x000002A5947D1B90>

Output: Sionna v1.0.2

None

[Mohkared]

Hi @merlinND,

I really appreciate your previous response.
I was wondering if there are any updates regarding this issue?
Thanks for your time!

[merlinND]

Hello @Mohkared,

I believe that you are simply seeing the effect of the merge_shapes=True option of load_scene(), where shapes with identical materials are merged into a single shape for increased efficiency: https://nvlabs.github.io/sionna/rt/api/scene.html#sionna.rt.load_scene

Let me know if I missed something.

[Mohkared]

Thanks @merlinND, that really worked!

[natanzi]

I have the same issue. Have you found the solution?

[Mohkared]

Hi @natanzi,

Unfortunately, no, I haven't found a solution yet.

What I've considered so far:

1. Using one of the existing materials as a default, loading the scene, creating a new material within the scene, and assigning it to the relevant objects. However, this approach has an issue—you can't access all objects after loading the scene, as mentioned in my earlier response.
2. Modifying the source code to add a new material. I had previously done this in Sionna v0.19.1, but I haven't tested it in v1.0.2 yet.

For option 2, I believe the path for adding an additional material is: .venv\Lib\site-packages\sionna\rt\radio_materials\itu.py

[mlouielu]

Hi @natanzi,

Unfortunately, no, I haven't found a solution yet.

What I've considered so far:

For option 2, I believe the path for adding an additional material is: .venv\Lib\site-packages\sionna\rt\radio_materials\itu.py

I think you can put in your material properties without adding in the source code by:

import sionna.rt as rt
import mitsuba as mi
rt.radio_materials.itu.ITU_MATERIALS_PROPERTIES["test"] = {(0.001, 100.0): (1.99,0,0.0047,1.0718)}
print(rt.radio_materials.itu.itu_material("test", mi.Float(33e9)))
# ([1.99], [0.199361])

[saria-lh]

@mlouielu
Unfortunately, it doesn't work. In itu_materials.py, the ITU_MATERIALS_PROPERTIES dictionary is loaded at import time, and it does not get updated after that (and hence the scene materials check fails). So afaik the best way to add a new material for a scene is to change the dictionary from the source code before importimg the lib and loading a scene with new materials.

[mlouielu]

@mlouielu Unfortunately, it doesn't work. In itu_materials.py, the ITU_MATERIALS_PROPERTIES dictionary is loaded at import time, and it does not get updated after that (and hence the scene materials check fails).

You can monkey patch a module after they imported in Python:

import sionna.rt as rt
rt.foo = 10
print(rt.foo)
# 10

So it turns out ITU_MATERIAL_COLORS also needs to update:

import sionna.rt as rt

rt.radio_materials.itu.ITU_MATERIALS_PROPERTIES["human"] = {
    (1.0, 10.0): (30.0, -0.4, 0.15, 1.30)
}
rt.radio_materials.itu_material.ITURadioMaterial.ITU_MATERIAL_COLORS["human"] = (
    0.539,
    0.027,
    0.147,
)

rt.load_scene("test.xml", merge_shapes=False)

$ python test_load_mat.py
jit_registry_shutdown(): leaking 7 instances of type "mitsuba::BSDF".
jit_registry_shutdown(): leaking 1 instances of type "mitsuba::Emitter".
jit_registry_shutdown(): leaking 1 instances of type "mitsuba::Shape".
jit_malloc_shutdown(): leaked
 - device memory: 1.378 MiB in 46 allocations

[merlinND]

Hello @Mohkared,

See also: #879, this will be improved in the next release.

Using one of the existing materials as a default, loading the scene, creating a new material within the scene, and assigning it to the relevant objects. However, this approach has an issue—you can't access all objects after loading the scene, as mentioned in my earlier #821 (reply in thread).

Please note the merge_shapes_exclude_regex option of load_scene(): https://nvlabs.github.io/sionna/rt/api/scene.html#sionna.rt.load_scene
If you can exclude the shapes for which you want to change the material from automatically being merged, then you'd still be able to assign a different material after loading.
For optimal performance, though, it's best to have a single merged shape for each material.

[kobina-sand]

Hi @Mohkared.

Sorry to ask this question under a closed thread. However, I'm wondering how one can export a scene from Sionna in the first place. I mean, suppose that I have all the data that I exported from blender (the .xml file and meshes directory). If I go on to add the various transmitters and receivers, how can I then export this enhanced scene from Sionna (in .xml or some other format)?

[Mohkared]

Hi @kobina-sand,

I don't mind at all! happy to help.

It is a great question. From my understanding of Sionna, it does not provide any export for scenes.
A possible approach is to save the properties and locations of transmitters and receivers separately in a structured file format such as .json, .yaml, or another format you prefer.

You might want to suggest this as a feature request in the Sionna community, as an export function could be a useful addition.

[ListenToAJ]

Hello @Mohkared,

I am also sorry to ask under the closed thread, but how exactly did you resolve the issue with XML and undefined materials? I have a single mesh with a custom defined material in old Sionna exactly as you did, but merge_shapes does not change anything. I was hoping of a way to apply the custom material before loading in scene from XML, but I have not been able to do that either.

[Mohkared]

Hi @ListenToAJ,

Glad I could help.
This is a known bug and should be fixed in a future update (see #879).

I fixed it by editing the Sionna source code to add my custom materials manually.