Improving speed with Ray-cast in UE4

问题

I am currently developing a lidar sensor model using Ray-cast. A 16 channel sensor rotating at 10Hz should produce 300000 points. I can use 300000 Ray-cast operations to get this result but the performance is very weak (frame rate falls to 8 when motion is given to the sensor). Is there any other better way or algorithms I can use?

Requirement :

To scan 360 degrees: Horizontal
-25 to 15 degrees: Vertical
300000 scans

Here is what I'm using:

for (auto i = 0u; i < 3125; ++i){
  for (auto Channel = 0u; Channel < 16; ++Channel){
    FVector Point(0,0,0);
    float DistanceToHitPoint = 0;
    uint8_t Row = 0;
    uint8_t Class = 0u;
    double Intensity = 0;
    float Aoi = 0;
    const float Angle =  std::fmod(CurrentHorizontalAngle + AngleDistanceOfLaserMeasure * i,  360.0f);
    auto timestamp = static_cast<uint32_t>(GetEpisode().GetElapsedGameTime()* pow(10,6));
    ShootLaser(Channel, Angle, Point, DistanceToHitPoint, Row, Aoi, Class);
    if(Description.EnergyEffect && (DistanceToHitPoint != 0)){
        bool isQualified = IsPointIntensityValid(DistanceToHitPoint, Aoi, "test", Row, Intensity);
        LidarMeasurement.WritePoint(Channel, Point, Intensity, Class);
        LidarServer.fill_block(Angle, DistanceToHitPoint, Row, Description.ReturnMode, timestamp);
        continue;
    }
    LidarMeasurement.WritePoint(Channel, Point, Intensity, Class);
    LidarServer.fill_block(Angle, DistanceToHitPoint, Row, Description.ReturnMode, timestamp);

  }
}
const float HorizontalAngle = std::fmod(CurrentHorizontalAngle + AngleDistanceOfTick, 360.0f);
LidarMeasurement.SetHorizontalAngle(HorizontalAngle);

For 1500000 Raycast operation per second above code is used. I am trying to run the loops within 0.033 seconds(30fps). However, simulation fps turns out to be 2 or 3 fps after running this code. Is there any alternative to use Raycast more efficiently.

回答1:

To simulate lidar you can use depth buffer of SceneCaptureComponent2D.

Create render target texture with format: RTF R16f
Create SceneCaptureComponent2D, assign target texture, set CaptureSource -> SceneDepth in R
Create Material with TextureObjectParameter, sample and divide by max_lidar_distance value in cm
Create DynamicMaterialInstance, set TextureParameterValue to target texture
Now you have scene depth rendered to texture, can be copied to main memory for other processing.

Check screenshots and example project: https://drive.google.com/open?id=1TImwJXmk5syvcPdPCylKXaaSCP99UI-m

来源：https://stackoverflow.com/questions/58930543/improving-speed-with-ray-cast-in-ue4

标签

unreal-engine4

raycasting