Is this page helpful?

RTX Acoustic Sensor#

RTX Acoustic sensors simulate ultrasonic wave propagation at render time on the GPU with RTX hardware. Their results are written to the GenericModelOutput AOV, similar to RTX Lidar and Radar sensors.

Overview#

RTX Acoustic sensors are rendered using OmniAcoustic prims, with the OmniSensorGenericAcousticWpmAPI schema applied. After attaching a render product to the OmniAcoustic prim, and setting the GenericModelOutput AOV on the render product, the RTXSensor renderer writes acoustic simulation results to the AOV.

For complete documentation on all acoustic schema attributes and the underlying Wave Propagation Model (WPM), see the Omniverse Acoustic Extension documentation.

Note

Earlier releases referred to this sensor as the “Ultrasonic” sensor (or “USS”). The Omniverse plugin has been renamed to “Acoustic”; if you previously used omni.kit.commands.execute("IsaacSensorCreateRtxUltrasonic", ...) in isaacsim.sensors.rtx, see RTX Sensors for the migration to Acoustic / AcousticSensor.

Unlike Lidar and Radar sensors, acoustic sensors do not produce a 3D point cloud. Instead, they produce signal ways — amplitude samples for each transmitter–receiver pair on each channel. The GenericModelOutput element fields have the following meaning for acoustic sensors:

Field

Meaning

x

Transmitter sensor mount ID

y

Receiver sensor mount ID

z

Channel ID

scalar

Amplitude sample value

Sensor Mounts and Receiver Groups#

Acoustic sensors use multi-apply schemas to define sensor mounts and receiver groups:

  • Sensor mounts (OmniSensorWpmAcousticSensorMountAPI) define the physical positions and orientations of transducers (transmitters and receivers). Each mount is an instance with a unique name (for example, m001, m002).

  • Receiver groups (OmniSensorWpmAcousticRxGroupAPI) define logical groupings of receivers by specifying which mount indices belong to the group. Each group is an instance with a unique name (for example, g001).

These schemas are applied automatically when the corresponding attribute prefixes are provided in the attributes dictionary.

How to Create an RTX Acoustic Sensor#

The isaacsim.sensors.experimental.rtx extension provides the Acoustic class for creating RTX Acoustic sensors. An equivalent menu entry is also registered by the isaacsim.sensors.rtx.ui extension for UI-driven creation.

Create an RTX Acoustic Sensor From the Create Menu#

To create a generic RTX Acoustic sensor from the Isaac Sim UI:

  • Main menu: Create > Sensors > RTX Acoustic > NVIDIA > Generic RTX Acoustic

  • Viewport context menu (right-click in the viewport): Create > Isaac > Sensors > RTX Acoustic > NVIDIA > Generic RTX Acoustic

Both entries create an OmniAcoustic prim with the OmniSensorGenericAcousticWpmAPI schema applied, at the next available path. If a prim is selected at creation time, the new sensor is parented under the selected prim; otherwise it is created at the stage root.

The menu entry creates a bare prim with no sensor mounts or receiver groups configured. To author the multi-apply schemas (OmniSensorWpmAcousticSensorMountAPI, OmniSensorWpmAcousticRxGroupAPI) and tune attributes such as omni:sensor:WpmAcoustic:centerFrequency, either edit the prim in the property panel after creation, or use the Acoustic class for programmatic setup as shown below.

The RTX Acoustic submenu also auto-populates additional vendor entries from the SUPPORTED_ACOUSTIC_CONFIGS dict in isaacsim.sensors.experimental.rtx, so OEM acoustic asset USDs registered there appear in the menu automatically.

Create an RTX Acoustic Sensor Using the Acoustic Class#

The Acoustic class creates or wraps an OmniAcoustic prim with the appropriate schemas applied.

Run this snippet in the Script Editor (Window > Script Editor).

import numpy as np
from isaacsim.sensors.experimental.rtx import Acoustic

# Create an RTX Acoustic sensor with a center frequency and two sensor mounts.
acoustic = Acoustic(
    path="/World/acoustic",
    tick_rate=20.0,
    translations=np.array([0.0, 0.0, 1.0]),
    attributes={
        "omni:sensor:WpmAcoustic:centerFrequency": 40000.0,
        # Sensor mount positions (transmitter/receiver locations)
        "omni:sensor:WpmAcoustic:sensorMount:m001:position": (0.0, 0.0, 0.0),
        "omni:sensor:WpmAcoustic:sensorMount:m002:position": (0.1, 0.0, 0.0),
        # Receiver group combining both mounts
        "omni:sensor:WpmAcoustic:rxGroup:g001:receiverIndices": [0, 1],
    },
)

The snippet above creates an OmniAcoustic prim at /World/acoustic with:

  • A center frequency of 40,000 Hz (ultrasonic)

  • Two sensor mounts at positions (0, 0, 0) and (0.1, 0, 0)

  • A receiver group combining both mounts

Note

Acoustic.create() accepts config (from isaacsim.sensors.experimental.rtx.SUPPORTED_ACOUSTIC_CONFIGS) or usd_path (mutually exclusive), plus attributes for prim-attribute overrides — including the multi-apply OmniSensorWpmAcousticSensorMountAPI / OmniSensorWpmAcousticRxGroupAPI / OmniSensorWpmAcousticFiringSeqAPI schema attributes — and the plural transform arrays (positions=[[...]] / translations=[[...]] / orientations=[[...]] / scales=[[...]]; N=1). Additional USD schemas via schemas=[...] are accepted by the Acoustic(...) constructor — pass them through Acoustic(...) directly if you need them, since Acoustic.create() does not currently forward schemas.

Tick Rate#

Warning

In Isaac Sim 6.0 GA, RTX Acoustic autotriggers regardless of omni:sensor:tickRate attribute. This will be corrected in a future release.

The tick_rate parameter (Hz) controls how frequently the sensor renders. A value of 0 (the default) enables autotrigger mode, where the sensor renders every simulation frame. This maps to the omni:sensor:tickRate prim attribute.

Run this snippet in the Script Editor (Window > Script Editor).

from isaacsim.sensors.experimental.rtx import Acoustic

# Render at 10 Hz regardless of simulation frame rate.
acoustic = Acoustic.create("/World/Acoustic", tick_rate=10.0)

Auxiliary Output Level#

RTX Acoustic exposes auxiliary data through the aux_output_level constructor parameter. Valid values are "NONE" (default) and "BASIC".

Run this snippet in the Script Editor (Window > Script Editor).

from isaacsim.sensors.experimental.rtx import Acoustic

acoustic = Acoustic.create("/World/Acoustic", aux_output_level="BASIC")

See Auxiliary Output Level and the GenericModelOutput RenderVar for the full attribute-flow explanation and the migration from the removed per-modality auxOutputType attribute, and Known issue: last-attach-wins propagation of GMO channels for a known issue when multiple RTX sensors with different auxiliary levels share a stage. See RTX Sensor Annotators for the per-level field listing.

How to Collect Data from an RTX Acoustic Sensor#

Use the AcousticSensor runtime class to attach annotators and retrieve data:

Run this snippet in the Script Editor (Window > Script Editor).

from isaacsim.sensors.experimental.rtx import Acoustic, AcousticSensor, parse_generic_model_output_data

acoustic = Acoustic.create("/World/Acoustic")

sensor = AcousticSensor(acoustic, annotators=["generic-model-output"])
data, info = sensor.get_data("generic-model-output")
gmo = parse_generic_model_output_data(data)

# gmo.x      -> transmitter mount IDs
# gmo.y      -> receiver mount IDs
# gmo.z      -> channel IDs
# gmo.scalar -> amplitude values

Refer to Reading Data from the GenericModelOutput Buffer for more details on the GenericModelOutput buffer.

Standalone Examples#

Basic Creation

# Create an acoustic sensor with two mounts and a receiver group
./python.sh standalone_examples/api/isaacsim.sensors.experimental.rtx/create_acoustic_basic.py

Data Inspection

# Inspect acoustic GenericModelOutput data and signal ways
./python.sh standalone_examples/api/isaacsim.sensors.experimental.rtx/inspect_acoustic_gmo.py

Note

Refer to the Isaac Sim Conventions documentation for a complete list of Isaac Sim conventions.