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.