Scene Objects

A scene is made of scene objects. Examples include cars, trees, buildings, furniture, etc. A scene object is characterized by its geometry and material (RadioMaterial) and implemented as an instance of the SceneObject class.

Scene objects are uniquely identified by their name. To access a scene object, the get() method of Scene may be used. For example, the following code snippet shows how to load a scene and list its scene objects:

scene = load_scene(sionna.rt.scene.munich)
print(scene.objects)

To select an object, e.g., named “Schrannenhalle-itu_metal”, you can run:

my_object = scene.get("Schrannenhalle-itu_metal")

You can then set the RadioMaterial of my_object as follows:

my_object.radio_material = "itu_wood"

class sionna.rt.SceneObject(mi_mesh=None, name=None, fname=None, radio_material=None, remove_duplicate_vertices=False)[source]

Class implementing a scene object

Scene objects can be either created from an existing Mitsuba shape or by loading a mesh from a file. In the latter case, a name and radio material for the scene object must be provided.

To create a scene object from a mesh file, use the following approach:

obj = SceneObject(fname=sionna.rt.scene.sphere,
                name="sphere",
                radio_material=ITURadioMaterial(name="sphere-material",
                                                itu_type="metal",
                                                thickness=0.01))

To instantiate a scene object using a Mitsuba shape, follow these steps:

mesh = load_mesh(sionna.rt.scene.sphere)
obj = SceneObject(mi_mesh=mesh,
                  name="sphere",
                  radio_material=ITURadioMaterial(name="sphere-material",
                                                itu_type="metal",
                                                thickness=0.01))

Parameters:

mi_mesh (typing.Optional[mitsuba.Mesh]) – Mitsuba shape. Must be provided if fname is None.
name (typing.Optional[str]) – Object name. Must be provided if fname is not None.
fname (typing.Optional[str]) – Filename of a valid mesh ( “.ply” | “.obj”). Must be provided if mi_mesh is None.
radio_material (typing.Optional[sionna.rt.radio_materials.radio_material_base.RadioMaterialBase]) – Radio material of the object. Must be provided if fname is not None.
remove_duplicate_vertices (bool)

clone(name=None, as_mesh=False, props=None)[source]

Creates a clone of the current scene object

The clone will have the same geometry and material properties as the original object but will be assigned a new name.

Parameters:

name (typing.Optional[str]) – Name (id) of the cloned object. If None, the clone will be named as <original_name>-clone.
as_mesh – If set to True, the clone will be returned as a mitsuba.Mesh object. Otherwise, a sionna.rt.SceneObject will be returned.
props (typing.Optional[mitsuba.Properties]) – Pre-populated properties to be used in the new Mitsuba shape. Allows overriding the BSDF, emitter, etc.

Return type:

sionna.rt.scene_object.SceneObject | mitsuba.Mesh

Returns:

A clone of the current object

look_at(target)[source]

Sets the orientation so that the x-axis points toward a position

Parameters:: target (mitsuba.Point3f | sionna.rt.radio_devices.radio_device.RadioDevice | str) – A position or the name or instance of an object in the scene to point toward to

property mi_mesh

Get/set the Mitsuba shape

Type:: mi.Mesh

property name

Name

Type:: str

property object_id

Identifier

Type:: int

property orientation

Get/set the orientation [rad] specified through three angles \((\alpha, \beta, \gamma)\) corresponding to a 3D rotation as defined in (3)

Type:: mi.Point3f

property position

Get/set the position vector [m] of the center of the object. The center is defined as the object’s axis-aligned bounding box (AABB).

Type:: mi.Point3f

property radio_material

Get/set the radio material of the object. Setting can be done by using either an instance of RadioMaterialBase or the material name (str).

Type:: RadioMaterialBase

property scaling

Get the scaling in the coordinate system of the object. If a scalar value is provided, the object is uniformly scaled across all dimensions by that value. Alternatively, if a vector is provided, the object is scaled independently along the x, y, and z axes according to the respective components of the vector, within the object’s coordinate system.

Type:: mi.Float | mi.Vector3f

property scene

Get/set the scene to which the object belongs. Note that the scene can only be set once.

Type:: sionna.rt.Scene

property velocity

Get/set the velocity vector [m/s]

The velocity must to be set at least once before it can be differentiated.

Type:: mi.Vector3f