Omniverse Radar Extension

Introduction

The Radar Sensor extension consists of models and OmniGraph nodes for various post-processing functions (e.g., transcoding Radar data into vendor-specific formats).

Currently, the extension supports one model:

• WpmDmatApproxRadar

This model has its own parameterization and at least one post-processing OmniGraph definition that specifies the processing pipeline nodes with default parameters.

Multiple post-processing OmniGraphs can exist for the same Radar model, each with unique parameter values and/or different node configurations.

“WpmDmatApprox” stands for “Wave Propagation Model Detection Matrix Approximation”. It uses the Wave Propagation Model (WPM) to ensure high fidelity while maintaining real-time capability. Key features include:

• Multiple bounces

• Support for different materials and improved radiometry

• Antenna gain patterns

• Multiple scan configurations (e.g. near and far scan) per Radar instance

Example Radar Prim

This is an example of how to define a Radar sensor in USD:

def OmniRadar "generic_radar" (
    doc = """Defines an instance of a radar that uses WPM DMAT approximation model"""
    prepend apiSchemas = ["OmniSensorGenericRadarWpmDmatAPI", "OmniSensorGenericRadarWpmDmatScanCfgAPI:s002"]
)
{
    # Global radar parameters from OmniSensorGenericRadarWpmDmatAPI
    float omni:sensor:tickRate = 20.0
    token omni:sensor:WpmDmat:auxOutputType = "NONE"
    token omni:sensor:WpmDmat:elementsCoordsType = "SPHERICAL"
    token omni:sensor:WpmDmat:outputFrameOfReference = "SENSOR"
    float[] omni:sensor:WpmDmat:customFrameOfReferenceTrafo = [0,0,0,0,0,0]
    float omni:sensor:WpmDmat:wavelengthmm = 3.9
    uint omni:sensor:WpmDmat:tracetreedepth = 4
    uint omni:sensor:WpmDmat:instancetimeoffsetusec = 5000
    token omni:sensor:WpmDmat:cfarmode = "2D"
    token omni:sensor:WpmDmat:antennagainmode = "COSINEFALLOFF"

    # First scan configuration (short range, wide angle)
    token omni:sensor:WpmDmat:scan:s001:elevMode = "NO_EL"
    float omni:sensor:WpmDmat:scan:s001:maxRangeM = 50
    float omni:sensor:WpmDmat:scan:s001:maxAzAngDeg = 75
    float omni:sensor:WpmDmat:scan:s001:maxElAngDeg = 20
    float omni:sensor:WpmDmat:scan:s001:raysPerDeg = 8.0
    uint omni:sensor:WpmDmat:scan:s001:timeOffsetUsec = 0
    float omni:sensor:WpmDmat:scan:s001:powerFactor = 1.0
    bool omni:sensor:WpmDmat:scan:s001:binsFromSpec = true
    bool omni:sensor:WpmDmat:scan:s001:enAngAliasing = false
    bool omni:sensor:WpmDmat:scan:s001:detValFromBinIdx = false
    float omni:sensor:WpmDmat:scan:s001:rangeResM = 0.4
    float omni:sensor:WpmDmat:scan:s001:velResMps = 0.147
    float omni:sensor:WpmDmat:scan:s001:boreAzResDeg = 1.3
    float omni:sensor:WpmDmat:scan:s001:boreElResDeg = 5.0
    uint omni:sensor:WpmDmat:scan:s001:rBins = 112
    uint omni:sensor:WpmDmat:scan:s001:vBins = 160
    uint omni:sensor:WpmDmat:scan:s001:azBins = 12
    uint omni:sensor:WpmDmat:scan:s001:elBins = 2
    uint omni:sensor:WpmDmat:scan:s001:cfarRnT = 1
    uint omni:sensor:WpmDmat:scan:s001:cfarRnG = 0
    uint omni:sensor:WpmDmat:scan:s001:cfarVnT = 1
    uint omni:sensor:WpmDmat:scan:s001:cfarVnG = 0
    uint omni:sensor:WpmDmat:scan:s001:cfarAznT = 1
    uint omni:sensor:WpmDmat:scan:s001:cfarAznG = 0
    uint omni:sensor:WpmDmat:scan:s001:cfarElnT = 1
    uint omni:sensor:WpmDmat:scan:s001:cfarElnG = 0
    float omni:sensor:WpmDmat:scan:s001:cfarMinVal = 7e-17
    float omni:sensor:WpmDmat:scan:s001:cfarOffset = 1.0
    float omni:sensor:WpmDmat:scan:s001:cfarNoiseMean = 0.0
    float omni:sensor:WpmDmat:scan:s001:cfarNoiseSDev = 0.0
    float[] omni:sensor:WpmDmat:scan:s001:maxVelMpsSequence = [50.0, 55.0]
    float[] omni:sensor:WpmDmat:scan:s001:rcsTuningCoefficients = [-12, 150, 0.0]
    float omni:sensor:WpmDmat:scan:s001:azimuthRadNoiseMean = 0.0
    float omni:sensor:WpmDmat:scan:s001:azimuthRadNoiseSDev = 0.0
    float omni:sensor:WpmDmat:scan:s001:elevationRadNoiseMean = 0.0
    float omni:sensor:WpmDmat:scan:s001:elevationRadNoiseSDev = 0.0
    float omni:sensor:WpmDmat:scan:s001:velocityNoiseMean = 0.0
    float omni:sensor:WpmDmat:scan:s001:velocityNoiseSDev = 0.0
    float omni:sensor:WpmDmat:scan:s001:rangeNoiseMean = 0.0
    float omni:sensor:WpmDmat:scan:s001:rangeNoiseSDev = 0.0
    float omni:sensor:WpmDmat:scan:s001:exponentialDecayFactor = 1.0

    # Second scan configuration (long range, narrow angle)
    token omni:sensor:WpmDmat:scan:s002:elevMode = "POS_EL"
    float omni:sensor:WpmDmat:scan:s002:maxRangeM = 300
    float omni:sensor:WpmDmat:scan:s002:maxAzAngDeg = 9
    float omni:sensor:WpmDmat:scan:s002:maxElAngDeg = 7
    # Define more parameters for s002 analogously to s001...

    def RenderProduct "RenderedOutputs"
    {
        uniform int2 resolution = (1280, 720)
        rel camera = <../../generic_radar>
        rel orderedVars = [
            <SupportedOutputs/RtxSensorCpu>,
            <SupportedOutputs/RtxSensorGpu>,
            <SupportedOutputs/RtxSensorGmo>,
            <SupportedOutputs/RtxSensorMetadata>,
        ]

        def Scope "SupportedOutputs"
        {
            def RenderVar "RtxSensorCpu"
            {
                uniform string sourceName = "RtxSensorCpu"
            }
            def RenderVar "RtxSensorGpu"
            {
                uniform string sourceName = "RtxSensorGpu"
            }
            def RenderVar "RtxSensorGmo"
            {
                uniform string sourceName = "GenericModelOutput"
            }
            def RenderVar "RtxSensorMetadata"
            {
                string sourceName = "RtxSensorMetadata"
            }
        }
    }
}

Setting Radar attributes

There are many attributes specific to OmniRadar prims that must be set to configure sensor behavior. The Radar sensor simulation supports multiple scan patterns, allowing a Radar to behave differently, e.g. in a near range and a far range scan. Usually, a configuration is supplied with the goal of bringing the simulated sensor’s behavior as close to the real sensor as possible.

In the Radar sensor’s prim, parameters of the Radar can be set by

prepending them with <parameterType> omni:sensor:WpmDmat:<parameterName> = <value>

For example

uint omni:sensor:WpmDmat:TraceTreeDepth = 4

Sensor-Level Parameters

To build a custom parameterization, there are some parameters that are set once for each sensor and are the same across all of the sensor’s scan patterns:

Attribute	Description	Unit	Allowed Values
WaveLengthMm	Wavelength of the Radar	mm	3.9
TraceTreeDepth	Depth of the ray tree build while traversing the scene. A bigger depth allows for realistic effects like multi bounce, while a shallower depth will increase performance		Positive integer
InstanceTimeOffsetUsec	Time offset of this Radar instance to simulate continuous firing in a group of Radars	μs	Any float
CfarMode	2D: Only range and velocity dimensions are considered for CFAR processing 4D: Range, velocity, azimuth, and elevation dimensions are considered for CFAR processing		“2D”, “4D”
AntennaGainMode	Antenna gain profile		“COSINEFALLOFF”,”CONSTANT”
NumScans	The number of scan patterns that the sensor supports. If a number of two is given, the following parameters need to be repeated for each scan pattern, as described below.		Positive integer

The following parameters have to be set per scan, where the total number of scans is determined by the omni:sensor:WpmDmat:NumScans value.

The parameters that describe a scan are defined in the following way:

<parameterType> omni:sensor:WpmDmat:scan<Idx>:<parameterName> = <value>

For example

float omni:sensor:WpmDmat:scan1:RaysPerDeg = 10.0

Warning

The scan index starts at 1, not at 0.

General Scan Parameters

The following parameters are provided once for each scan and influence the general behavior of a Radar sensor. RaysPerDeg influences how many rays the sensor shoots per degree and together with the parameters that determine the sensor’s field-of-view (FoV), the total number of rays is calculated. Changing this value increases fidelity but decreases performance.

Attribute	Description	Unit	Allowed Values
RaysPerDeg	Ray density. The total number of rays is depended on MaxAzAngDeg and MaxElAngDeg as well		Positive integer
TimeOffsetUsec	time offset of the scan from the frame time to simulate non-equidistant scans	μs	Any float
PowerFactor	Total output power of Radar	W	Positive float
EnAngAliasing	Enable angular aliasing		true, false
DetValFromBinIdx	If true, detection value derived from bin index; if false, more accurate inside cell		true, false
ElevMode	Elevation mode; FULL_EL:pos neg elevation POS_EL:only pos elevation NO_EL: elevation=0		“FULL_EL”, “POS_EL”, “NO_EL”

Range and Angle Parameters

These values are set per scan and determine the detection range of the sensor as well as the FoV. These values are usually found in a Radar sensor’s spec sheet and can easily be set to approach the behavior of a given real sensor.

Attribute	Description	Unit	Allowed Values
MaxRangeM	Maximum detection range of the scan	m	Positive float
MaxAzAngDeg	Maximum azimuth angle, FOV is 2x this value	deg	Positive float
MaxElAngDeg	Maximum elevation angle, FOV is 2x this value	deg	Positive float
RangeResM	Range resolution, only if BinsFromSpec is true	m	Positive float
VelResMps	Velocity resolution, only if BinsFromSpec is true	m/s	Positive float
BoreAzResDeg	Azimuth resolution at bore sight, only if BinsFromSpec is true	deg	Positive float
BoreElResDeg	Elevation resolution at bore sight, only if BinsFromSpec is true	deg	Positive float

Bin Parameters

These values are set per scan as well. The number of bins that the Radar sensor uses to bin the returns can either be calculated by the sensor from the values in the previous table or explicit values can be given to the sensor. If BinsFromSpec is true, the values for RBins, VBins, AzBins and ElBins will be ignored.

Attribute	Description	Unit	Allowed Values
BinsFromSpec	Flag to determine if bins are derived from resolution parameters		true, false
RBins	Number of range bins of this scan. Only if BinsFromSpec is false.		Positive integer
VBins	Number of velocity bins of this scan. Only if BinsFromSpec is false.		Positive integer
AzBins	Number of azimuth bins of this scan. Only if BinsFromSpec is false.		Positive integer
ElBins	Number of elevation bins of this scan. Only if BinsFromSpec is false.		Positive integer

CFAR (Constant False Alarm Rate) Parameters

The Cfar-parameters are set per scan. A Cfar-Implementation is used to filter all returns that the sensor received for only the ones that are targets of interest.

Attribute	Description	Unit	Allowed Values
CfarRnT	CFAR number of range test cells		Positive integer
CfarRnG	CFAR number of range guard cells		Positive integer
CfarVnT	CFAR number of velocity test cells		Positive integer
CfarVnG	CFAR number of velocity guard cells		Positive integer
CfarAznT	CFAR number of azimuth test cells		Positive integer
CfarAznG	CFAR number of azimuth guard cells		Positive integer
CfarElnT	CFAR number of elevation test cells		Positive integer
CfarElnG	CFAR number of elevation guard cells		Positive integer
CfarMinVal	CFAR minimum value for detection, cells below are discarded		Positive float
CfarOffset	Multiplied with raw CFAR noise level. Set to 1 if no scaling of noise is desired		Positive float
CfarNoiseMean	Mean noise level used in CFAR		Any float
CfarNoiseSDev	Standard deviation of noise in CFAR		Positive float

Noise Parameters

The noise parameters are set per scan. The Noise parameters category defines the characteristics of the noise affecting the Radar sensor’s measurements. These parameters help simulate real-world imperfections and variability in the sensor’s readings.

Attribute	Description	Unit	Allowed Values
AzimuthRadNoiseMean	Mean noise added to azimuth radial measurements	rad	Any float
AzimuthRadNoiseSDev	Standard deviation of azimuth radial noise at boresight	rad	Positive float
ElevationRadNoiseMean	Mean noise added to elevation radial measurements	rad	Any float
ElevationRadNoiseSDev	Standard deviation of elevation radial noise at boresight	rad	Positive float
VelocityNoiseMean	Mean noise added to velocity measurements	m/s	Any float
VelocityNoiseSDev	Standard deviation of noise added to velocity measurements	m/s	Positive float
RangeNoiseMean	Mean noise added to range measurements	m	Any float
RangeNoiseSDev	Standard deviation of noise added to range measurements	m	Positive float

Sequence and Coefficient Parameters

The sequence parameters are set per scan. The RcsTuningCoefficients array is especially useful for tuning a Radar simulation to behave as similar as possible to the real Radar.

Attribute	Description	Unit	Allowed Values
MaxVelMpsSequence	An array representing the maximum unambiguous velocity sequence of the scan, expressed in meters per second. This parameter models the varying maximum velocity that the Radar can unambiguously measure over different time intervals.	m/s	Array of floats
RcsTuningCoefficients	The RcsTuningCoefficients are a list of parameters that influence the computation of the RCS. RcsTuningCoefficients[0] is a threshold value and only returns with a RCS [dBsm] > RcsTuningCoefficients[0] will be accepted. RcsTuningCoefficients[1] is a scaling parameter that’s multiplied with the RCS before it is converted to dBsm. RcsTuningCoefficients[2] is a scaling parameter that is multiplied with normalized noise that is added to the RCS after conversion to dBsm. A value 0 will therefore not add any noise.		Array of 3 floats

Radar Point Cloud

The Radar extension uses the GenericModelOutput format. Refer to the documentation for more information on GenericModelOutput.