readLAScatalog: Create an object of class LAScatalog

In lidR: Airborne LiDAR Data Manipulation and Visualization for Forestry Applications

Create an object of class LAScatalog

Description

Create an object of class LAScatalog from a folder or a collection of filenames. A LAScatalog is a representation of a collection of las/laz files. A computer cannot load all the data at once. A LAScatalog is a simple way to manage all the files sequentially. Most functions from lidR can be used seamlessly with a LAScatalog using the internal LAScatalog processing engine. To take advantage of the LAScatalog processing engine the user must first adjust some processing options using the appropriate functions. Careful reading of the LAScatalog class documentation is required to use the LAScatalog class correctly.

readLAScatalog is the original function and always works. Using one of the read*LAScatalog functions adds information to the returned object to register a point-cloud type. Registering the correct point type may improve the performance of some functions by enabling users to select an appropriate spatial index. See spatial indexing. Notice that by legacy and for backwards-compatibility reasons readLAScatalog() and readALSLAScatalog() are equivalent because lidR was originally designed for ALS and thus the original function readLAScatalog() was (supposedly) used for ALS.

Usage

readLAScatalog(
  folder,
  progress = TRUE,
  select = "*",
  filter = "",
  chunk_size = 0,
  chunk_buffer = 30,
  ...
)

readALSLAScatalog(folder, ...)

readTLSLAScatalog(folder, ...)

readUAVLAScatalog(folder, ...)

readDAPLAScatalog(folder, ...)

catalog(folder, ...)

Arguments

folder	string. The path of a folder containing a set of las/laz files. Can also be a vector of file paths.
progress, select, filter, chunk_size, chunk_buffer	Easily accessible processing options tuning. See LAScatalog-class and engine_options.
...	Extra parameters to list.files. Typically recursive = TRUE. Propagates also to readLAScatalog

Value

A LAScatalog object

Examples

# A single file LAScatalog using data provided with the package
LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
ctg = readLAScatalog(LASfile)
plot(ctg)

## Not run: 
ctg <- readLAScatalog("</path/to/folder/of/las/>")

# Internal engine will sequentially process chunks of size 500 x 500 m
opt_chunk_size(ctg) <- 500

# Internal engine will align the 500 x 500 m chunks on x = 250 and y = 300
opt_alignment(ctg) <- c(250, 300)

# Internal engine will not display a progress estimation
opt_progress(ctg) <- FALSE

# Internal engine will not return results into R.
# Instead it will write results in files.
# Files will be named e.g.
# filename_256000_1.ext
# filename_257000_2.ext
# filename_258000_3.ext
# ...
opt_output_files(ctg) <- "/path/filename_{XBOTTOM}_{ID}"

# More details in the documentation
help("LAScatalog-class", "lidR")
help("engine_options", "lidR")

## End(Not run)

lidR documentation built on Sept. 11, 2024, 5:21 p.m.