RTX Radar Sensor#

../_images/isaacsim_sensors_rtx_radar_node_overview_warehouse.png

RTX Radar sensors are simulated at render time on the GPU with RTX hardware. Their results are then copied to the GenericModelOutput AOV for use.

Warning

Motion BVH Must Be Enabled for RTX Radar

RTX Radar requires Motion BVH to be enabled for the Doppler effect—and therefore RTX Radar entirely—to be modeled correctly. Without Motion BVH enabled, RTX Radar will not produce accurate results.

Motion BVH is disabled by default in Isaac Sim for performance reasons. You must explicitly enable it before using RTX Radar.

To enable Motion BVH, add the following command line arguments when launching Isaac Sim:

--/renderer/raytracingMotion/enabled=true \
--/renderer/raytracingMotion/enableHydraEngineMasking=true \
--/renderer/raytracingMotion/enabledForHydraEngines='0,1,2,3,4'

Or in standalone Python, pass enable_motion_bvh=True to the SimulationApp constructor.

Refer to How to Enable Motion BVH for complete instructions.

Overview#

Note

In Isaac Sim 4.5 and earlier, RTX sensors were based on Camera prims. If the Camera prim’s sensorModelPluginName attribute was set to omni.sensors.nv.radar.wpm_dmatapprox.plugin, then the Camera prim was used to render the Radar. The Radar was configured using a JSON file whose filename (without extension) was set in the Camera prim’s sensorModelConfig attribute, assuming the file was present in a folder specified by the app.sensors.nv.radar.profileBaseFolder setting. Support for Camera prims as RTX Radars was deprecated in Isaac Sim 5.0.

RTX Radars are rendered using OmniRadar prims, with the OmniSensorGenericRadarWpmDmatAPI schema applied, as configured by attributes on the prim. After attaching a render product to the OmniRadar prim, and setting the GenericModelOutput AOV on the render product, the RTXSensor renderer will write Radar render results to the AOV.

How to Create an RTX Radar#

The isaacsim.sensors.rtx extension provides one API for creating RTX Radars. In addition, the omni.replicator.core extension provides even lower-level APIs for creating OmniRadar prims (including batch creation) and attaching render products to them.

Create an RTX Radar Using Command#

The IsaacSensorCreateRtxRadar command creates a generic OmniRadar prim with the appropriate schemas applied, or a Camera prim with the appropriate attributes to support deprecated workflows.

import omni
from pxr import Gf

# Specify attributes to apply to the ``OmniRadar`` prim.
sensor_attributes = {"omni:sensor:tickRate": 10}

_, sensor = omni.kit.commands.execute(
    "IsaacSensorCreateRtxRadar",
    translation=Gf.Vec3d(0, 0, 0),
    orientation=Gf.Quatd(1, 0, 0, 0),
    path="/radar",
    parent=None,
    visibility=False,
    variant=None,
    force_camera_prim=False,
    **sensor_attributes,
)

The example command above creates an OmniRadar prim in the stage at the specified translation with the specified orientation, at path /radar. The prim is set to be invisible in the stage. The prim’s omni:sensor:tickRate attribute is set to 10 Hz from 20 Hz (default).

Review the OmniSensorGenericRadarWpmDmatAPI schema in the omni.usd.schema.omni_sensors extension to learn which attributes can be set on the OmniRadar prim.

The Isaac Sim UI after running the ``IsaacSensorCreateRtxRadar`` command shown above.

Setting force_camera_prim to True will instead create an invisible Camera prim at the specified translation and orientation.

Annotators can then be attached to the OmniRadar prim to collect and visualize the Radar results. Details about available annotators can be explored here.

How to Collect Data from an RTX Radar#

The recommended method for collecting data from an RTX Radar is to use Replicator Annotators, similar to RTX Lidar.

The IsaacExtractRTXSensorPointCloudNoAccumulator annotator works with both OmniLidar and OmniRadar prims, extracting point cloud data from the GenericModelOutput buffer every frame.

Refer to RTX Sensor Annotators for the full list of available annotators.

Visualizing RTX Radar Output#

Debug Draw#

The Debug Draw Extension can be used to visualize RTX Radar point cloud output in the viewport.

The standalone example create_radar_basic.py demonstrates using Debug Draw to visualize RTX Radar output:

./python.sh standalone_examples/api/isaacsim.sensors.rtx/create_radar_basic.py

For more information on Debug Draw APIs, refer to Debug Drawing Extension API and Util Snippets.

Doppler Effects#

Important

Motion BVH must be enabled for the Doppler effect to be modeled correctly in RTX Radar simulations. Refer to How to Enable Motion BVH for instructions on enabling Motion BVH.

Sensor Materials#

The material system for RTX Radar allows content creators to assign sensor material types to partial material prim names on a USD stage. Radar return behavior depends on material properties (for example, emissivity, reflectivity), as described below.

RTX Sensor Non-Visual Materials

Standalone Examples#

For examples of creating and collecting data from RTX Radar, refer to the following:

Basic Creation and Visualization

# Basic radar creation with debug draw visualization
./python.sh standalone_examples/api/isaacsim.sensors.rtx/create_radar_basic.py

Data Collection and Inspection

# Inspect radar GenericModelOutput (GMO) data
./python.sh standalone_examples/api/isaacsim.sensors.rtx/inspect_radar_gmo.py

Note

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