identify function

Retrieve individual pulses, flightlines or scanlines

Retrieve each individual pulse, individual flightline or individual scanline and assigns a number to each point. The LAS object must be properly populated according to LAS specifications otherwise users could find unexpected outputs.

retrieve_pulses(las)

retrieve_flightlines(las, dt = 30)

retrieve_scanlines(las)

Arguments

• las: A LAS object
• dt: numeric. The threshold time-lag used to retrieve flightlines

Returns

An object of class LAS

Details

• retrieve_pulses: Retrieves each individual pulse. It uses GPS time. An attribute pulseID is added in the LAS object
• retrieve_scanlines: Retrieves each individual scanline. When data are sampled according to a saw-tooth pattern (oscillating mirror), a scanline is one line, or row of data. The function relies on the GPS field time to order the data. Then, the ScanDirectionFlag attribute is used to retrieve each scanline. An attribute scanlineID is added in the LAS object
• retrieve_flightlines: Retrieves each individual flightline. It uses GPS time. In a continuous dataset, once points are ordered by GPS time, the time between two consecutive points does not exceed a few milliseconds. If the time between two consecutive points is too long it means that the second point is from a different flightline. The default threshold is 30 seconds. An attribute flightlineID is added in the LAS object.

Examples

LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
las <- readLAS(LASfile)

las <- retrieve_pulses(las)
las

las <- retrieve_flightlines(las)
#plot(las, color = "flightlineID")