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HELIOS

The Heidelberg LiDAR Operations Simulator (HELIOS) is a software package for interactive real-time simulation and visualization of terrestrial, mobile and airborne laser scanning surveys written in Java.

HELIOS-FWF

HELIOS ver. 2.0 - Full-WaveForm implementation within the Heidelberg LiDAR Operations Simulator.

Features

The following FWF features are included to the latest FWF HELIOS build:

  • BRDF reflectance model.
  • Gaussian decomposition to extract multiple echo returns (point coordinates,intensity,width,return number). Based on least square fitting library.

Future features will include:

  • More sophisticated atmospheric scattering model.
  • Per-scanner based input waveform profile of the outgoing pulse.

Configuration variables (for <FWFSettings > in <survey> XML file)

  • numTimeBins (integer) - Number of bins to discretize the temporal domain of individual return.
  • numFullwaveBins (integer) - Total number of bins to discretize the entire temporal domain of FWF signal.
  • winSize (integer) - Number of neigbhouring samples to check (i.e. 1D window size) when finding local maxima for Gaussian decomposition.
  • peakEnergy (double) - Scanner's peak emitting energy [W].
  • apertureDiameter (double) - Scanner's aperture diameter [m].
  • atmosphericVisbility (double) - Decrease of intensity due atmospheric scattering. Within range [0, 1].
  • scannerEfficiency (double) - Efficiency of the scanner. Within range of [0, 1].
  • scannerWaveLength (double) - Scanner's operating wavelength [ns].
  • beamDivergence_rad (double) - Scanner's beam divergence angle [rad]. Used if not defined in <scanner>.
  • pulseLength_ns (double) - Scanner's pulse length [ns]. Used if not defined in <scanner>.
  • beamSampleQuality (integer) - Quality of spatial discretization of the subrays (higher value = more subrays within the laser cone). Default set to 3.

Modification of MTF (obj material) file

  • helios_reflectance (double) - Define the reflectance (albedo) of the given material. Within range [0, 1].

Output point format

point.x point.y point.z intensity echoWidth FWFIndex returnNumber returnNumPerPulse objectId

  • point (double) - Coordinates of 3D captured points from echo returns in FWF signal.
  • intensity (double) - Intensity of the return [W].
  • echoWidth (double) - The full width at half maximum of the echo-return [ns].
  • returnNumber (integer) - The corresponding return number.
  • returnNumPerPulse (integer) - Number of returns per pulse.
  • FWFIndex (integer) - The index of the FWF signal.
  • objectId (string) - The id of the hit object.

Output FWF format

FWFIndex beamOrigin.x beamOrigin.y beamOrigin.z beamDir.x beamDir.y beamDir.z minTime maxTime gpsTime FWFIntensities

  • FWFIndex (integer) - The index of the FWF signal (in order to match corresponding points)
  • beamOrigin (double) - 3D point of the beam's origin.
  • beamOrigin (double) - 3D vector of the beam's direction.
  • minTime (double) - FWF signal beginning time [ns].
  • maxTime (double) - FWF signal ending time [ns].
  • gpsTIme (integer) - Simulated GPS time.
  • FWFIntensities (double) - Intensities of the entire FWF signal. Number defined with numFullwaveBins.