RTX Lidar Config Parameters

There are base parameters that affect the entire Lidar, and there are emitter parameters. An emitter state is an array of emitter parameters with one entry for each individual emitter. At least one emitter state is mandatory, but multiple emitter states can exist, and will be cycled through according to the base parameters.

Parameters that are only for Rotary, or only for Solid State will be marked with (Rotary) or (Solid State) after their name. It is not part of their name, and if there are two parameters of the same name it is because they mean different things for the different scan types.

Base Parameters

The following parameters are mandatory, and the config file won’t load correctly without them.

scanType: set to “rotary” for spinning Lidar, and “solidState” for stationary lidar.
nearRangeM: the min valid range in meters

Warning

rangeOffset and minDistBetweenEchos must both be below nearRangeM. [IMPORTANT] minDistBetweenEchos defaults to 0.4 meters if not set, therefore if nearRangeM is < 0.4 then minDistBetweenEchos is required to be set set to <= nearRangeM to get all outputs.
farRangeM: the max valid range in meters
[start,end]AzimuthDeg: start/end azimuth (horizontal angle) for the filed of view (fov) in degrees
[up,down]ElevationDeg: upper/lower elevation (vertical angle) for the fov in degrees
rangeResolutionM: range resolution in m
rangeAccuracyM: range accuracy in m
avgPowerW: average power of laser in W. This is a per pulse power.
waveLengthNm: wavelength of laser in nanometer
pulseTimeNs: laser pulse time in ns
maxReturns: number of returns of the Lidar (Using 1 return has an optimized path)
reportRateBaseHz: the number of times the firing pattern is shot per second
scanRateBaseHz: (Rotary) frequency of the sensor, i.e. how many times it spins per second
scanRateBaseHz: (Solid State) frequency of the sensor, i.e. number of fill firing cycles per second
numberOfEmitters: number of emitters per sensor position (tick)
numLines: (Solid State) Number of rows per full scan.
numRaysPerLine: (Solid State) Number of emitters in a row.

Optional Parameters

The following parameters are optional

rangeOffset: start beam firing after this distance

This is helpful for Lidar inside housing geometry.
intensityProcessing: specifies the in render intensity correction method
This parameter only affects the raw non scaled intensity available from the ReadRTXLidarData node, and is in the range [0.0, 1.0]
- “normalization” - normalizes based on the Rayleigh range
- “correction” - a range based correction that is not derived from a gaussian beam profile, and treats all ranges past 100m the same
- Any other string - fallback behavior
intensityMappingType: specifies the mapping type for post-process intensity from the ComputeRTXLidarPointCloud node
- “LINEAR” - uses only the intensityScalePercent, and maps [0, 1] to [0, intensityScalePercent/100]
rayType: specifies the modeled ray type
- “IDEALIZED” - emitter is modeled as an idealized (single) ray (Less GPU Memory used)
- “GAUSSIAN_BEAM” - emitter is simulated as an gaussian beam
- “UNIFORM_BEAM” - emitter is simulated as a uniform beam
effectiveApertureSize: effective aperture size of collector in meters
focusDistM: Focusing distance in m, distance to beam waist
valid[Start,End]AzimuthDeg: star/end azimuth in degrees for capped sensor fov
[hor,vert]ResolutionDeg: horizontal/vertical resolution in degrees
minDistBetweenEchos: return ranges below this threshold will be set to 0. Defaults to 0.4 meters
minReflectance: minimum reflectance at a minReflectanceRange
minReflectanceRange: specified range with minReflectance in m
[azimuth,elevation]ErrorMean: error profile average in degrees for sensor azimuth/elevation position
[azimuth,elevation]ErrorStd: error profile standard deviation in degrees for sensor azimuth/elevation position
numberOfChannels: number of channels = detectors per sensor position(tick)

Multiple emitters can map to the same channel.
rangeCount: number of different emitter ranges, and size of the ranges array

The index of the range each emitter uses is stored in the rangeId emitter state parameter.
ranges: list of max/min pairs of size rangeCount

If range and rangeCount is not used, then the [near,far]RangeM parameters are used for all emitters.
stateResolutionStep: (Rotary) step in degrees used to cycle through emitter states if emitterStateCount > 1

The rotary Lidar has only have one state per tick (one shooting of the pattern)! For example, a stateResolutionStep = 0.1 means that it will fire a pattern every \(0.1deg\) with a different state. If the delta between different ticks (\(\frac{ 360}{reportRateBaseHz}\)) is also \(0.1deg\), then state changes every tick. However, if there are \(10\) ticks in \(0.1deg\) then each of the \(10\) ticks will fire with the same emitter state.
stateResolutionStep: (Solid State) number of frames per state
emitters: (Rotary) holds the single emitter state if emitterStateCount is NOT set
emitterStateCount: number of different emitter states
emitterStates: holds the list or emitter states if emitterStateCount is set

Emitter State Parameters

Emitter states hold properties that are arrays of size numberOfEmitters. The following parameters are mandatory, and the config file won’t load correctly without them.

azimuthDeg: azimuth deviation in degrees of the emitter as measured from the angle the firing starts at
elevationDeg: elevation deviation in degrees, must be between [up,down]ElevationDeg
fireTimeNs: firing time of emitter (delta to tick start time) in ns

It should be in the range \([0, 1.000.000.000/reportRateBaseHz]\).

Optional Emitter Parameters

The following parameters are optional

focalDistM: focal distance in m
focalSlope: focal slope in m
reportRateDiv: report rate divisor
bank: the line index (Solid State) or beam bank (Rotary), should be filled if the line/bank information is important in post processing
channelId: channel of beam
rangeId: emitter range id, should be filled if ranges and rangeCount are used