Firing Sequence Files

Description

Firing sequence files are used to describe a LiDAR's emission pattern. These files embed several information like the firing time, firing angles and source power, that will be used during the simulation to draw the scanning sequence.

Two types of firing sequence files are available in Speos allowing you to define the emission pattern of a scanning or a rotating LiDAR.

Scanning Sequence File

Scanning Sequence File Overview

Scanning sequence files describe the horizontal and vertical emission pattern for one beam or multiple beams of the LiDAR. They are required for both scanning and rotating LiDAR sensors.

For more information on how to generate a scanning sequence file, refer to Generating a Scanning Sequence File.

*.OPTScanSequence Scanning Sequence File Content

The *.OPTScanSequence scanning sequence file comprises the following parameters:

• Type of pulses: DIRAC, Gaussian, Rectangular, Triangular

• Width of pulse (s): duration of one pulse in seconds (s), Δt (only for Gaussian, Triangular, Rectangular pulse types)

  Note: When using the Dirac pulse type, the Width of pulse is skipped.

Triangular pulse type	Rectangular pulse type	Gaussian pulse type

• Shooting Time (s): time when the pulse is emitted in seconds (s)
• Pulse energy (J): Energy of the pulse in Joules

• Pulse type: From pulses, DIRAC, Gaussian, Rectangular, Triangular

  Note: From pulse means that the Pulse type inherits the Type of pulses value.

• Pulse width (s): duration of one pulse in seconds (s), Δt (only for Gaussian, Triangular, Rectangular pulse types)

  Note: If you enter a Pulse width value different from the Width of pulse value, the Pulse width has priority.
  Note: When using the Dirac pulse type, the Width of pulse is skipped.
• Azimuth angle (°): Azimuth angles within the range [0;360[ expressed in degrees

• Elevation angle (°): Elevation angles within the range [-90;90] expressed in degrees

  Note: Azimuth and elevation angles are expressed with respect to the source's axis system of the LiDAR sensor.

  Azimuth angle (horizontal pattern)	Elevation angle (vertical pattern)

• Position X Y Z (mm): Starting position of the beam with respect to the source's axis system of the LiDAR sensor. That means the beam can be offset.
• Emissive Surface Description: corresponds to the emissive surface of the beam.
  • Surface shape: Point, Rectangular, Elliptic
  • Width: width of the beam (for Rectangular and Elliptic shapes)
  • Height: height of the beam (for Rectangular and Elliptic shapes)
  • Psi angle (°): corresponds to the rotation of the surface shape around the Z axis
• Intensity Description

  • Intensity type: From source definition, Sampled, Gaussian

    If you set From source definition, the Source - Intensity section's parameters from the LiDAR sensor definition are used.

    If you set Sampled, define an Intensity file (IES file)

    If you set Gaussian define the three following Gaussian parameters.

  • Intensity file: IES file that will be converted into a readable intensity distribution when generating the *.OPTScanSequence (or *.txt) file. The intensity value is defined on 2π steradian.
  • Gaussian FWHM along X and Y (°): Gaussian intensity distribution of the beam
  • Gaussian total angle (°): Total angle of the beam for a Gaussian intensity distribution
  
  
  
• Spectrum description

  • Spectrum type: From source definition, Sampled, Monochromatic

    If you set From source definition, the Source - Spectrum section's parameters from the LiDAR sensor definition are used.

    If you set Sampled, define an Spectrum file

    If you set Monochromatic defined Wavelength (nm)

  • Spectrum file: Specific spectrum file for the beam
  • Wavelength (nm): wavelength for monochromatic spectrum type

*.txt Scanning Sequence File Content

(line 1) ANSYS – LiDAR scanning sequence file v1.0
(line 2) Comments
(line 3) Pulse Type (DIRAC or Gaussian or Rectangular or Triangular)
(line 4) Width of the pulse Δt
(line 5) Total number of firing samples
(line 6) Fire_time_1 Fire_pulse_energy_1 Azimuth_angle_1 Elevation_angle_1
(line 7) Fire_time_2 Fire_pulse_energy_2 Azimuth_angle_2 Elevation_ angle_2
...
(line 5+N) Fire_time_N Fire_pulse_energy_N Azimuth_angle_N Elevation_angle_N

ANSYS - LiDAR scanning sequence file v1.0
Scanning Sequence File Example
Rectangular
2
4
0.0 3.00E-7 60 0
1.0 3.00E-7 25 0
2.0 3.00E-7 -15 0
3.0 3.00E-7 -45 0

Rotating Sequence File

Rotating sequence files describe the rotation pattern of the LiDAR system. The rotating sequence file and scanning pattern file need to be combined to model the definition of a rotating LiDAR. Indeed, with this configuration, the scanning pattern (defined in the scanning sequence file) is repeated sequentially for each rotation step of the LiDAR (defined in the rotating sequence file).

Azimuth angles - Rotating LiDAR rotation step