Package rlas. June 11, 2018

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1 Type Package Package rlas June 11, 2018 Title Read and Write 'las' and 'laz' Binary File Formats Used for Remote Sensing Data Version Date Read and write 'las' and 'laz' binary file formats. The LAS file format is a public file format for the interchange of 3-dimensional point cloud data between data users. The LAS specifications are approved by the American Society for Photogrammetry and Remote Sensing < The LAZ file format is an open and lossless compression scheme for binary LAS format versions 1.0 to 1.3 < URL BugReports License GPL-3 Depends R (>= 3.0.0) Imports data.table,rcpp,uuid LazyData true RoxygenNote LinkingTo Rcpp Suggests testthat Encoding UTF-8 NeedsCompilation yes Author Jean-Romain Roussel [aut, cre, cph], Florian De Boissieu [aut, ctb] (Enable the support of.lax file and extra byte attributes), Martin Isenburg [cph] (Is the author of the LASlib and LASzip libraries), David Auty [ctb] (Reviewed the documentation), Pierrick Marie [ctb] (Helped to compile LASlib code in R) Maintainer Jean-Romain Roussel <jean-romain.roussel.1@ulaval.ca> 1

2 2 check_data Repository CRAN Date/Publication :10:52 UTC R topics documented: check_data header_add_extrabytes header_create read.las read.lasheader readlasdata readlasheader write.las writelas writelax Index 12 check_data Check if data and headers are correct las files are normalized files. The check_* functions test whether either the dataset is valid, the header is valid, or if the header is in accordance with the data. check_data(data) check_header(header) check_data_vs_header(header, data,...) data a data.frame or a data.table containing a point cloud header a list containing the header of a las file... internal use only

3 header_add_extrabytes 3 header_add_extrabytes Variable length records tools Functions that update a header to describe variable length records according to the LAS specifications header_add_extrabytes(header, data, name, desc) header_add_extrabytes_manual(header, name, desc, type, offset = NULL, scale = NULL, max = NULL, min = NULL, NA_value = NULL) header data name desc type scale, offset min, max NA_value list vector. Data that must be added in the extrabytes attributes. character. The name of the extrabytes attributes to add in the file. character. The description of the extrabytes attributes to add in the file. integer. The data type of the extrabytes attributes (page 25 of the spec). numeric. The scale and offset of the data. NULL if not relevant. numeric or integer. The minimum and maximum value of the data. NULL if not relevant. numeric or integer. NA is not a valid value. At writing time it will be replaced by this value that will be considered as NA. NULL if not relevant. Examples data = data.frame(x = c( , , ), Y = c( , , ), Z = c( , , ), gpstime = c( , , ), Intensity = c(82l, 54L, 27L), ReturnNumber = c(1l, 1L, 2L), NumberOfReturns = c(1l, 1L, 2L), ScanDirectionFlag = c(1l, 1L, 1L), EdgeOfFlightline = c(1l, 0L, 0L), Classification = c(1l, 1L, 1L), ScanAngle = c(-21l, -21L, -21L), UserData = c(32l, 32L, 32L), PointSourceID = c(17l, 17L, 17L), treeid = c(1l, 1L, 1L)) lasheader = header_create(data)

4 4 header_create lasheader[["variable Length Records"]] lasheader = header_add_extrabytes(lasheader, data$treeid, "treeid", "An id for each tree") lasheader[["variable Length Records"]] header_create Public header block tools Create or update a header for a las file from a dataset. A las file consists of two parts. A header that describes the data and the data itself. These functions make valid headers (public header block only) that can be used in write.las. header_create(data) header_update(header, data) data header data.frame or data.table list. A header Details header_create makes a full header from data. header_update modifies the information that needs to be updated. But most of the original information is not modified, for example point data format is kept as is. A list containing the metadata required to write a las file. Examples lasdata = data.frame(x = c( , , ), Y = c( , , ), Z = c( , , ), gpstime = c( , , ), Intensity = c(82l, 54L, 27L), ReturnNumber = c(1l, 1L, 2L), NumberOfReturns = c(1l, 1L, 2L), ScanDirectionFlag = c(1l, 1L, 1L), EdgeOfFlightline = c(1l, 0L, 0L), Classification = c(1l, 1L, 1L), ScanAngle = c(-21l, -21L, -21L), UserData = c(32l, 32L, 32L),

5 read.las 5 lasheader = header_create(lasdata) PointSourceID = c(17l, 17L, 17L), treeid = c(1l, 1L, 1L)) read.las Read data from a.las or.laz file Reads data from.las or.laz files in format 1 to 4 according to LAS specifications and returns a data.table labeled according to LAS specifications. See the ASPRS documentation for the LAS file format. The optional parameters enable the user to save memory by choosing to load only the fields they need. Moreover, the function provides a streaming filter to load only the points of interest into the memory and hence avoids allocating any superfluous memory. read.las(files, select = "*", filter = "") files select filter array of characters character. select only columns of interest to save memory (see details) character. streaming filters - filter data while reading the file (see details) Details Select: the select argument specifies the data that 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, s - synthetic flag, k - key-point flag, w - withheld flag, 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 for the extra bytes data numbers 1 to 9. 0 enables all extra bytes to be loaded and * is the wildcard that enables everything to be loaded from the LAS file. Note that x, y, z are implicit and always loaded. xyzia is equivalent to ia. Filter: the filter argument allows filtering of the point cloud while reading files. rlas relies on the well-known LASlib library written by Martin Isenburg to read the binary files. Thus the package inherits the filter commands available in LAStools. To use these filters the user can pass the common commands from LAStools into the parameter 'filter'. Type rlas:::lasfilterusage() to display the LASlib documentation and the available filters. A data.table

6 6 read.lasheader Examples lazfile <- system.file("extdata", "example.laz", package="rlas") lasdata <- read.las(lazfile) lasdata <- read.las(lazfile, filter = "-keep_first") lasdata <- read.las(lazfile, filter = "-drop_intensity_below 80") lasdata <- read.las(lazfile, select = "xyzia") read.lasheader Read header from a.las or.laz file Reads header from.las or.laz files in format 1 to 4 according to LAS specifications and returns a list labeled according to LAS specifications. See the ASPRS documentation for the LAS file format. read.lasheader(file) file filepath character string to the.las or.laz file A list See Also Other rlas: write.las Examples lazfile <- system.file("extdata", "example.laz", package="rlas") lasheader <- read.lasheader(lazfile)

7 readlasdata 7 readlasdata Read data from a.las or.laz file (deprecated) Use read.las readlasdata(files, i = TRUE, r = TRUE, n = TRUE, d = TRUE, e = TRUE, c = TRUE, a = TRUE, u = TRUE, p = TRUE, rgb = TRUE, t = TRUE, filter = "", eb = 0) files i r n d e c a u p rgb t filter eb filepath character string to the.las or.laz files logical. do you want to load the Intensity field? default: TRUE logical. do you want to load the ReturnNumber field? default: TRUE logical. do you want to load the NumberOfReturns field? default: TRUE logical. do you want to load the ScanDirectionFlag field? default: TRUE logical. do you want to load the EdgeOfFlightline field? default: TRUE logical. do you want to load the Classification field? default: TRUE logical. do you want to load the ScanAngle field? default: TRUE logical. do you want to load the UserData field? default: TRUE logical. do you want to load the PointSourceID field? default: TRUE logical. do you want to load R,G and B fields? default: TRUE logical. do you want to load gpstime fields? default: TRUE character. filter data while reading the file (streaming filter) without allocating any useless memory. (see Details). integer vector. which extra byte attributes to load (see LAS file format specs). default is 0 meaning that all extra fields will be loaded. c(1,3,7) to load the first, the third and the seventh extra byte attributes. None is numeric(0) or NULL. A data.table

8 8 write.las readlasheader (deprecated) Read header from a.las or.laz file (deprecated) Use read.lasheader readlasheader(file) file filepath character string to the.las or.laz file A list write.las Write a.las or.laz file Write a.las or.laz file. The user provides a table with the data in columns. Column names must respect the specified allowed names (see details). A correct and complete header must also be provided. This header can optionally be generated with header_create. write.las(file, header, data) file header data character. file path to.las or.laz file list. Can be partially recycled from another file (see read.lasheader) and updated with header_update or generated with header_create. data.frame or data.table that contains the data to write in the file. Column names must respect the imposed nomenclature (see details)

9 writelas 9 Details Allowed names are "X", "Y", "Z", "gpstime", "Intensity", "ReturnNumber", "NumberOfReturns", "ScanDirectionFlag", "EdgeOfFlightline", "Classification", "ScanAngle", "UserData", "PointSourceID", "R", "G", "B", "NIR". All other extra columns will be written in extra bytes attributes only if the header specifically states these data should be saved into extra bytes attributes. To use the full potential of the function write.las it is recommended users read the complete specifications of the LAS file format. Otherwise users can rely on automated procedures that are expected to be sufficient for most usages. void See Also Other rlas: read.lasheader Examples lasdata = data.frame(x = c( , , ), Y = c( , , ), Z = c( , , ), gpstime = c( , , ), Intensity = c(82l, 54L, 27L), ReturnNumber = c(1l, 1L, 2L), NumberOfReturns = c(1l, 1L, 2L), ScanDirectionFlag = c(1l, 1L, 1L), EdgeOfFlightline = c(1l, 0L, 0L), Classification = c(1l, 1L, 1L), ScanAngle = c(-21l, -21L, -21L), UserData = c(32l, 32L, 32L), PointSourceID = c(17l, 17L, 17L)) lasheader = header_create(lasdata) file = file.path(tempdir(), "temp.laz") write.las(file, lasheader, lasdata) writelas (deprecated) Write a.las or.laz file (deprecated) Use write.las writelas(file, header, X, Y, Z, gpstime, Intensity, ReturnNumber, NumberOfReturns, ScanDirectionFlag, EdgeOfFlightline, Classification, ScanAngle, UserData, PointSourceID, R, G, B)

10 10 writelax file header X Y Z gpstime Intensity character. filename of.las or.laz file list of character. The data for the file header properly labelled (see readlasheader) numeric array X data numeric array Y data numeric array Z data numeric array gpstime data integer array intensity data ReturnNumber integer array return number data NumberOfReturns integer array number of returns data ScanDirectionFlag integer array scan direction flag data EdgeOfFlightline integer array edge of flightline data Classification integer array classification data ScanAngle UserData PointSourceID R G B integer array scan angle data integer array user data data integer array point source id data integer array red data integer array green data integer array blue data void writelax Write a.lax file from a.las or.laz file Write a lax file from a las or laz file. A lax file is a tiny file which can come with a las or laz and which spatially index the data to make faster spatial queries. It has been invented by Martin Isenburg in LASlib. rlas support lax file and enable to write a lax file with default settings. For more options, use lasindex from binaries provided by LASlib (for more informations see references) writelax(file)

11 writelax 11 file character. filename of.las or.laz file References

12 Index check_data, 2 check_data_vs_header (check_data), 2 check_header (check_data), 2 header_add_extrabytes, 3 header_add_extrabytes_manual (header_add_extrabytes), 3 header_create, 4, 8 header_update, 8 header_update (header_create), 4 read.las, 5, 7 read.lasheader, 6, 8, 9 readlasdata, 7 readlasheader, 8, 10 write.las, 4, 6, 8, 9 writelas, 9 writelax, 10 12