readLAS: Read .las or .laz files

Description

Reads .las or .laz files in format 1 to 4 according to LAS specifications and returns an object of class LAS. If several files are given the returned LAS object is considered as one LAS file. The optional parameters enable the user to save a substantial amount of memory by choosing to load only the fields or points required. These internal options are much more memory-efficient than any other R code.

Usage

readLAS(files, select = "*", filter = "")

Arguments

files

array of characters or a LAScatalog object

select

character. select only columns of interest to save memory (see details)

filter

character. streaming filters - filter data while reading the file (see details)

Value

A LAS object

Details

Select: the 'select' argument specifies which data will actually be loaded. For example, 'xyzia' means that the x, y, and z coordinates, the intensity and the scan angle will be loaded. The supported entries are t - gpstime, a - scan angle, i - intensity, n - number of returns, r - return number, c - classification, u - user data, p - point source ID, e - edge of flight line flag, d - direction of scan flag, R - red channel of RGB color, G - green channel of RGB color, B - blue channel of RGB color, N - near infrared channel. Also numbers from 1 to 9 are available for the extra bytes data 1 to 9. 0 enables loading of all extra bytes and '*' is the wildcard and enables everything to be loaded from the LAS file. Note that x, y, z are implicit and always loaded. 'xyzia' is equivalent to 'ia'. Three extra data attributes can be computed on the fly with the following flags: P - pulse id, F - flightline id and C - color string. The symbol + is a shortcut for 'PFC'. Filter: the 'filter' argument allows filtering of the point cloud while reading files. This is much more efficient than lasfilter in many ways. If the desired filters are known before reading the file, the internal filters should always be preferred. The available filters are those from LASlib and can be found by running the following command: rlas:::lasfilterusage(). (see also rlas::read.las)

Examples

Run this code

# NOT RUN {
LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
las = readLAS(LASfile)
las = readLAS(LASfile, select = "xyz")
las = readLAS(LASfile, select = "xyzi", filter = "-keep_first")
las = readLAS(LASfile, select = "xyziar", filter = "-keep_first -drop_z_below 0")

# Negation of data is also available (all except intensity and angle)
las = readLAS(LASfile, select = "* -i -a")
# }