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"
    token omni:sensor:WpmDmat:scan:s001:datacubeMode = "FAST"
    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:enableRangeAliasing = 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

    # Signal processing parameters (when datacubeMode = "WAVEFORM")
    uint omni:sensor:WpmDmat:scan:s001:arrayAzimuthElements = 85
    uint omni:sensor:WpmDmat:scan:s001:arrayElevationElements = 14
    uint omni:sensor:WpmDmat:scan:s001:slowTimeSamples = 379
    uint omni:sensor:WpmDmat:scan:s001:fastTimeSamples = 625
    uint omni:sensor:WpmDmat:scan:s001:azimuthPaddingSamples = 128
    uint omni:sensor:WpmDmat:scan:s001:elevationPaddingSamples = 32
    uint omni:sensor:WpmDmat:scan:s001:slowTimePaddingSamples = 512
    uint omni:sensor:WpmDmat:scan:s001:fastTimePaddingSamples = 1024
    float omni:sensor:WpmDmat:scan:s001:azimuthElementSpacing = 0.00236
    float omni:sensor:WpmDmat:scan:s001:elevationElementSpacing = 0.00332
    float omni:sensor:WpmDmat:scan:s001:carrierFrequency = 77e9
    float omni:sensor:WpmDmat:scan:s001:chirpDuration = 6.4e-05
    float omni:sensor:WpmDmat:scan:s001:chirpBandwidth = 1.5e9
    float omni:sensor:WpmDmat:scan:s001:chirpRepetitionTime = 35e-06
    float omni:sensor:WpmDmat:scan:s001:frequencyStepBetweenChirps = 0.0
    float omni:sensor:WpmDmat:scan:s001:supportFactor = 1.0

    # Debug parameters for development
    bool omni:sensor:WpmDmat:scan:s001:debugForceDetection = false
    float omni:sensor:WpmDmat:scan:s001:debugForceRange = 20.0
    float omni:sensor:WpmDmat:scan:s001:debugForceV = 5.0
    float omni:sensor:WpmDmat:scan:s001:debugForceAz = 0.0
    float omni:sensor:WpmDmat:scan:s001:debugForceEl = 0.0

    # Second scan configuration (long range, narrow angle)
    token omni:sensor:WpmDmat:scan:s002:elevMode = "POS_EL"
    token omni:sensor:WpmDmat:scan:s002:datacubeMode = "FAST"
    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”

“CUSTOM”

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

EnableRangeAliasing

Enable range 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”

DatacubeMode

Datacube processing mode; FAST: traditional DMAT computation WAVEFORM: waveform approximation

“FAST”, “WAVEFORM”

RxAntennaAzDeg

Array of azimuth angles (in degrees) defining the antenna gain pattern grid for receiver

deg

Array of sorted floats

RxAntennaElDeg

Array of elevation angles (in degrees) defining the antenna gain pattern grid for receiver

deg

Array of sorted floats

RxAntennaCoGain

Array of co-polarization gains for receiver antenna (row-major order, size = ElSize * AzSize)

Array of floats

RxAntennaCrossGain

Array of cross-polarization gains for receiver antenna (row-major order, size = ElSize * AzSize)

Array of floats

TxAntennaAzDeg

Array of azimuth angles (in degrees) defining the antenna gain pattern grid for transmitter

deg

Array of sorted floats

TxAntennaElDeg

Array of elevation angles (in degrees) defining the antenna gain pattern grid for transmitter

deg

Array of sorted floats

TxAntennaCoGain

Array of co-polarization gains for transmitter antenna (row-major order, size = ElSize * AzSize)

Array of floats

TxAntennaCrossGain

Array of cross-polarization gains for transmitter antenna (row-major order, size = ElSize * AzSize)

Array of floats

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

ExponentialDecayFactor

Exponential decay factor for a contribution. The higher, the faster the contribution decreases with distance. Default should be 1.0.

Positive float

Signal Processing Parameters#

These parameters control advanced signal processing when DatacubeMode is set to “WAVEFORM”. They configure the waveform of a radar frame for enhanced processing.

Attribute

Description

Unit

Allowed Values

ArrayAzimuthElements

Number of azimuth antenna elements in the array

Positive integer

ArrayElevationElements

Number of elevation antenna elements in the array

Positive integer

SlowTimeSamples

Slow-time number of samples

Positive integer

FastTimeSamples

Fast-time number of samples

Positive integer

AzimuthPaddingSamples

Number of zero-padding samples in azimuth

Positive integer

ElevationPaddingSamples

Number of zero-padding samples in elevation

Positive integer

SlowTimePaddingSamples

Number of zero-padding samples in slow-time

Positive integer

FastTimePaddingSamples

Number of zero-padding samples in fast-time

Positive integer

AzimuthElementSpacing

Azimuth antenna element spacing

m

Positive float

ElevationElementSpacing

Elevation antenna element spacing

m

Positive float

CarrierFrequency

Carrier frequency

Hz

Positive float

ChirpDuration

Chirp duration

s

Positive float

ChirpBandwidth

Chirp bandwidth

Hz

Positive float

ChirpRepetitionTime

Chirp repetition time (>= chirp duration)

s

Positive float

FrequencyStepBetweenChirps

Frequency step between chirps

Hz

Positive float

SupportFactor

Support factor in units of main lobe width (1 = one main lobe)

Positive float

Debug Parameters#

These parameters enable forced detection modes for development and testing purposes.

Attribute

Description

Unit

Allowed Values

DebugForceDetection

Enable forced detection mode for debugging

true, false

DebugForceRange

Forced range value when debug mode is enabled

m

Positive float

DebugForceV

Forced velocity value when debug mode is enabled

m/s

Any float

DebugForceAz

Forced azimuth value when debug mode is enabled

deg

Any float

DebugForceEl

Forced elevation value when debug mode is enabled

deg

Any float

Radar Point Cloud#

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