LidarNoiseModel Class Reference

#include <LidarNoiseModel.h>

Static Public Member Functions
static bool	CheckSnowflakeHit (FHitResult &HitInfo, const FVector EndTrace, const FVector LidarLocation, const FWeatherParameters &WeatherParameters)

Static Private Member Functions
static bool	CheckSnowflakeHitWinterSim (FHitResult &HitInfo, const float PrecipitationAmount, const float ParticleSize, const FVector EndTrace, const FVector LidarLocation)
static float	CalculatePrecipitationClass (const float PrecipitationAmount, float ParticleSize)

Detailed Description

LidarNoiseModel is a static class for checking whether linetrace "hit" snowflake based on certain Simulation weather parameters and selected noise model formula.

WinterSim formula: Wintersim Lidar noise model formula was originally created in WinterSim project during the project in 2020-2022. See more about the project and Lidar analysis here: https://a3s.fi/swift/v1/AUTH_8811c563a60e4395828a2393f44e064b/website_documents/wintersim/WinterSim_LidarAnalysis.pdf https://www.frostbit.fi/en/portfolio/wintersim-2/ https://wintersim.fi/ The WinterSim formula was created by analysing gathered Lidar, camera and weather data during winter 2021-2022 with Ouster OS1 Lidar sensor in various weather conditions. The noise model creates noise to the end Lidar pointcloud output when following simulation weather conditions are met: 1) Temperature is below zero 2) Precipitation is over zero

Definition at line 29 of file LidarNoiseModel.h.

Member Function Documentation

CalculatePrecipitationClass()

float LidarNoiseModel::CalculatePrecipitationClass ( const float  PrecipitationAmount, float  ParticleSize  )

staticprivate

Calculates "precipitation class" based on rain and particle size.

Parameters

PrecipitationAmount	The amount of rain affecting the precipitation class, ranging from 0.0 to 100.0.
ParticleSize	The size of the precipitation particles, ranging from 0.0 to 100.0.

Returns

The calculated precipitation class.

Definition at line 57 of file LidarNoiseModel.cpp.

{
    float PrecipitationClass = 0;
 
    // Ensure ParticleSize is within the specified bounds (1.0 to 3.0) and adjust if necessary
    if (ParticleSize < 1.0f) ParticleSize = 1.0f;
    if (ParticleSize > 3.0f) ParticleSize = 3.0f;
 
    if (PrecipitationAmount > 0 && PrecipitationAmount <= 33.33f)           PrecipitationClass = 1 + ParticleSize;
    else if (PrecipitationAmount > 33.33 && PrecipitationAmount <= 66.66f)  PrecipitationClass = 2 + ParticleSize;
    else if (PrecipitationAmount > 66.66 && PrecipitationAmount <= 100.00f) PrecipitationClass = 3 + ParticleSize;
 
    return PrecipitationClass;
}

Referenced by CheckSnowflakeHitWinterSim().

CheckSnowflakeHit()

bool LidarNoiseModel::CheckSnowflakeHit ( FHitResult &  HitInfo, const FVector  EndTrace, const FVector  LidarLocation, const FWeatherParameters &  WeatherParameters  )

static

Evaluates whether a linetrace "intersects" with a snowflake within specific weather conditions, utilizing a designated noise model.

Parameters

NoiseModel	The noise model formula used to simulate lidar detection inaccuracies.
HitInfo	Reference to store the hit result details.
EndTrace	The end point of the linetrace.
LidarLocation	The starting point of the linetrace from the lidar device.
WeatherParameters	The environmental conditions affecting the detection probability.

Returns

bool Returns true if the linetrace is determined to intersect with a snowflake, false otherwise.

Definition at line 12 of file LidarNoiseModel.cpp.

{
    return CheckSnowflakeHitWinterSim(HitInfo, WeatherParameters.Precipitation, WeatherParameters.PrecipitationParticleSize, EndTrace, LidarLocation);;
}

References CheckSnowflakeHitWinterSim(), FWeatherParameters::Precipitation, and FWeatherParameters::PrecipitationParticleSize.

Referenced by ALidar::ShootLaser().

CheckSnowflakeHitWinterSim()

bool LidarNoiseModel::CheckSnowflakeHitWinterSim ( FHitResult &  HitInfo, const float  PrecipitationAmount, const float  ParticleSize, const FVector  EndTrace, const FVector  LidarLocation  )

staticprivate

Check snowflake hit using the WinterSim noise formula.

Returns

true if the line trace 'hit' a snowflake, false otherwise.

Definition at line 17 of file LidarNoiseModel.cpp.

{
    // Create random value between 0.0 and 1.0
    const float RandomValue = FMath::FRandRange(0.0, 1.0f);
 
    FVector MaxDistance = EndTrace;                                 // lidar max range
    FVector StartPoint = LidarLocation;                             // start point is lidar position
 
    float PrecipitationClass = CalculatePrecipitationClass(PrecipitationAmount, ParticleSize);
 
    if (HitInfo.bBlockingHit)
    {
        MaxDistance = HitInfo.ImpactPoint;
    }
 
    FVector DirectionVector = EndTrace - StartPoint;
    FVector NewStartPoint = StartPoint + 0.01 * DirectionVector;    // make start point away from center of lidar
    FVector NewVector = MaxDistance - NewStartPoint;                // new vector from new start point to end point
    FVector NewHitpoint = NewStartPoint + RandomValue * NewVector;  // generate new point from new start point to end point
    NewHitpoint *= 1e-2;
    float Distance = FVector::Dist(StartPoint, NewHitpoint) / 100;  // distance between NewHitpoint and NewStartPoint divided by 100 to get meters
 
    // Actual probability formula calculation
    const float ProbabilityFormula = PrecipitationClass / 10 * exp(-pow(Distance - (4 + 0.2 * PrecipitationClass), 2.0)
        / pow(2, 2.0)) + 0.2 * PrecipitationClass / 10 * exp(-pow(Distance - (7 + 0.2 * PrecipitationClass), 2.0) / pow(1, 2.0));
 
    // If RandomValue is smaller than ProbabilityFormula from formula we 'hit' the trace to snowflake
    bool HitSnowflake = RandomValue < ProbabilityFormula;
    if (HitSnowflake)
    {
        // Assign new hitpoint
        HitInfo.ImpactPoint = NewHitpoint;
 
        // To identify the snowflake later, set component to nullptr if hitpoint is snowflake
        HitInfo.Component = nullptr;
    }
 
    return HitSnowflake;
}

References CalculatePrecipitationClass().

Referenced by CheckSnowflakeHit().

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The documentation for this class was generated from the following files:

• Unreal/Agrarsense/Source/Agrarsense/Sensor/Lidar/LidarNoiseModel.h
• Unreal/Agrarsense/Source/Agrarsense/Sensor/Lidar/LidarNoiseModel.cpp