Error loading scene after update — HolderMaterial only allows one nested radio material

[madhumitha-murthy]

Hi,

My scene with default-bsdf worked fine before, but after updating Sionna, I get this error when loading:

ValueError: HolderMaterial only allows one nested radio material but found property "default-bsdf"

Could you help me understand what changed and how to fix it?
Thanks!

[merlinND]

Hello @madhumitha-murthy,

Please share the full scene so that we can have a look.

Is the BSDF default-bsdf a custom BSDF plugin? Did you make sure it is registered before loading the scene?

[madhumitha-murthy]

Hi Merlin,

I'm not using a custom BSDF plugin, in Blender I’ve simply set the surface to Diffuse BSDF. This worked before the update, but after updating Sionna I get the HolderMaterial error.

Below is the .xml file:

<scene version="2.1.0">

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

	<default name="spp" value="4096"/>
	<default name="resx" value="1920"/>
	<default name="resy" value="1080"/>

<!-- Camera and Rendering Parameters -->

	<integrator type="path" id="elm__0" name="elm__0">
		<integer name="max_depth" value="12"/>
	</integrator>
	<sensor type="perspective" id="Camera" name="Camera">
		<string name="fov_axis" value="x"/>
		<float name="fov" value="39.597752"/>
		<float name="principal_point_offset_x" value="0.000000"/>
		<float name="principal_point_offset_y" value="-0.000000"/>
		<float name="near_clip" value="0.100000"/>
		<float name="far_clip" value="100.000000"/>
		<transform name="to_world">
			<rotate x="1" angle="116.44070980054053"/>
			<rotate y="1" angle="5.419622430558914e-06"/>
			<rotate z="1" angle="-133.30805320118378"/>
			<translate value="7.358891 -6.925791 4.958309"/>
		</transform>
		<sampler type="independent" name="sampler">
			<integer name="sample_count" value="$spp"/>
		</sampler>
		<film type="hdrfilm" name="film">
			<integer name="width" value="$resx"/>
			<integer name="height" value="$resy"/>
		</film>
	</sensor>

<!-- Materials -->

	<bsdf type="twosided" id="mat-very_dry_ground" name="mat-very_dry_ground">
		<bsdf type="diffuse" name="bsdf">
			<rgb value="0.800000 0.800000 0.800000" name="reflectance"/>
		</bsdf>
	</bsdf>
	<bsdf type="twosided" id="mat-concrete" name="mat-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="diffuse" id="mat-brick" name="mat-brick">
		<rgb value="1.000000 0.000000 0.300000" name="reflectance"/>
	</bsdf>

<!-- Emitters -->

	<emitter type="point" id="emit-Light" name="emit-Light">
		<point name="position" x="-5.245534896850586" y="5.887098789215088" z="42.34650802612305"/>
		<rgb value="79.577469 79.577469 79.577469" name="intensity"/>
	</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-very_dry_ground" name="bsdf"/>
	</shape>
	<shape type="ply" id="mesh-Cube" name="mesh-Cube">
		<string name="filename" value="meshes/Cube.ply"/>
		<boolean name="face_normals" value="true"/>
		<ref id="mat-concrete" name="bsdf"/>
	</shape>
	<shape type="ply" id="mesh-map_3_osm_buildings" name="mesh-map_3_osm_buildings">
		<string name="filename" value="meshes/map_3_osm_buildings.ply"/>
		<boolean name="face_normals" value="true"/>
		<ref id="mat-brick" name="bsdf"/>
	</shape>

<!-- Volumes -->

</scene>

[merlinND]

Thanks for sharing the scene file. I'm not sure where default-bsdf comes from since it's not part of your scene.
But anyway, I think that the solution is in this comment: #951 (comment)

The error message and general convenience for specifying radio materials will be improved in the next version.

[madhumitha-murthy]

Thanks for the help! I followed the suggestion and updated the material setup as in the linked comment, it works now without the default-bsdf issue. Appreciate the quick guidance!