Help creating a scene with a custom radio material

[godOfToasters]

Hi, I am new to Sionna and I am having trouble getting scattering working. What I've done so far is create a .xml file with mitsuba and that is just a flat surface where I define the material as water and use that as the scene. This is where my first problem arises I get an error about holder material only allowing one nested radio material.
This is my code right now:

try:
    import sionna.rt as rt
except ImportError as e:
    import os
    os.system("pip install sionna-rt")
    import sionna.rt


%matplotlib inline
import matplotlib.pyplot as plt
import numpy as np

no_preview = True # Toggle to False to use the preview widget


from sionna.rt import load_scene, PlanarArray, Transmitter, Receiver, Camera,\
                      PathSolver, RadioMapSolver, subcarrier_frequencies, RadioMaterial

scene = load_scene(r"C:\Users\xxx\OneDrive\Desktop\sionna simulation\ocean.xml", merge_shapes=False) # Merge shapes to speed-up computations


scene.tx_array = PlanarArray(num_rows=1,
                             num_cols=1,
                             vertical_spacing=0.5,
                             horizontal_spacing=0.5,
                             pattern="tr38901",
                             polarization="V")

scene.rx_array = PlanarArray(num_rows=1,
                             num_cols=1,
                             vertical_spacing=0.5,
                             horizontal_spacing=0.5,
                             pattern="dipole",
                             polarization="cross")

tx = Transmitter(name="tx",
                 position=[1,4,10],
                 display_radius=1)

scene.add(tx)

rx = Receiver(name="rx",
              position=[-2,2,5],
              display_radius=1)

rx2 = Receiver(name="rx2",
               position=[2, 2, 7],  # <-- Change this position as desired
               display_radius=1)
rx3 = Receiver(name="rx3",
               position=[-2, -2, 5],  # <-- Change this position as desired
               display_radius=1)



scene.add(rx)
scene.add(rx2)
scene.add(rx3)

tx.look_at(rx) # Transmitter points towards receiver


p_solver  = PathSolver()


paths = p_solver(scene=scene,
                 max_depth=3, # Maximum number of reflections
                 los=True,
                 specular_reflection=True,
                 diffuse_reflection=False,
                 refraction=False,
                 synthetic_array=True,
                 seed=41)


scene.preview(paths=paths, clip_at=20, radio_map=None)

and this is my xml file

<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-mat-water" name="mat-mat-water">
		<bsdf type="principled" name="bsdf">
			<rgb value="0.150449 0.516010 0.800189" 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>

<!-- Emitters -->

	<emitter type="constant" id="World" name="World">
		<rgb value="1.000000 1.000000 1.000000" 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-mat-water" name="bsdf"/>
	</shape>

<!-- Volumes -->

</scene>

[merlinND]

Hello @godOfToasters,

Please have a look at the following discussion, and feel free to post again if your problem is not resolved:

• Custom Material Issue in Sionna 1.1 (Bug #879 Still Present?) #931 (comment)
• How to reuse my scenes in the new Sionna v1.0.2 #821

[godOfToasters]

I got the holder material error to go away but now I'm stuck with a new error.

RuntimeError Traceback (most recent call last)
Cell In[2], line 23
17 from sionna.rt import load_scene, PlanarArray, Transmitter, Receiver, Camera,
18 PathSolver, RadioMapSolver, subcarrier_frequencies, RadioMaterial
22 # Load integrated scene
---> 23 scene = load_scene(r"C:\Users\xxx\OneDrive\Desktop\sionna simulation\ocean.xml", merge_shapes=False) # Merge shapes to speed-up computations
26 # Configure antenna array for all transmitters
27 scene.tx_array = PlanarArray(num_rows=1,
28 num_cols=1,
29 vertical_spacing=0.5,
30 horizontal_spacing=0.5,
31 pattern="tr38901",
32 polarization="V")

File c:\Users\xxx\OneDrive\Desktop\sionna simulation\sionna-env\lib\site-packages\sionna\rt\scene.py:1054, in load_scene(filename, merge_shapes, merge_shapes_exclude_regex)
1052 try:
1053 thread.set_file_resolver(fres)
-> 1054 mi_scene = mi.load_string(processed)
1055 finally:
1056 thread.set_file_resolver(fres_old)

RuntimeError: ​[xml.cpp:1082] Error while loading "" (near line 6, col 10): could not instantiate bsdf plugin of type "radio-material": Traceback (most recent call last):
[xml.cpp:1082] File "C:\Users\xxx\AppData\Local\Temp\ipykernel_37536\3115785135.py", line 22, in
[xml.cpp:1082] File "c:\Users\xxx\OneDrive\Desktop\sionna simulation\sionna-env\lib\site-packages\sionna\rt\radio_materials\radio_material.py", line 160, in init
[xml.cpp:1082] TypeError: LambertianPattern() takes no arguments

I looked through those threads and its still rather confusing. Do I need to edit the source code?

[godOfToasters]

I've kind of found a work around for now. I edited the box.ply file to expand it and thin it out and I am using the wet_ground material in place of my custom material. I am editing the properties like this scene.get("box").radio_material.scattering_coefficient = 0.5. Is this a fix? My goal is calculate the impulse response time with scattering over the ocean. Is that possible this way?