catalog_retile: Retile a catalog

Description

Splits or merges files to reshape the original catalog files (.las or .laz) into smaller or larger files. It also enables the addition or removal of a buffer around the tiles. The new files are written in a dedicated folder. The function first displays the layout of the new tiling pattern and then asks the user to validate the command.

Usage

catalog_retile(ctg, path, prefix, ext = c("las", "laz"), alignment = c(0,
  0), ...)

Arguments

ctg

A LAScatalog object

path

string. The folder where the new files should be saved.

prefix

character. The prefix of the written file name. It can be missing, in which case if the catalog is processed by file, the original name of the file will be retained.

ext

character. The format of the written files. Can be ".las" or ".laz".

alignment

numeric vector. A vector of size 2 (x and y coordinates, respectively) to align the pattern. By default the alignment is made along (0,0) as in all LAScatalog processes, meaning the edge of a virtual tile will belong on x = 0 and y = 0 and all the the others will be multiples of the tiling size.

...

extra parameter 'filter' to pass to readLAS (readLAS is not actually called but the parameter can be passed anyway).

Value

A new LAScatalog object

Details

Internally the function reads and writes the clusters defined by the internal processing options of a LAScatalog (see also catalog). Thus the function is flexible and enables the user to retile the dataset, retile while adding or removing a buffer (negative buffers are allowed), or optionally to compress the data by retiling without changing the pattern but by changing the format (las/laz).

Note that this function is not actually very useful since lidR manages everything (clipping, processing, buffering, ...) internally using the proper options. Thus, retiling may be useful for working in other software for example, but not in lidR.

Examples

Run this code

# NOT RUN {
ctg = catalog("path/to/catalog")

# Create a new set of .las files 500 by 500 wide in the folder
# path/to/new/catalog/ and iteratively named Forest_001.las, Forest_002.las
# Forest_003.las, and so on.

buffer(ctg) = 0
by_file(ctg) = FALSE
tiling_size(ctg) = 500
newctg = catalog_retile(ctg, "path/to/new/catalog", "Forest_")

# Create a new set of .las files equivalent to the original one
# but extended with a 50 m buffer in the folder path/to/new/catalog/
# and iteratively named named after the original files.

buffer(ctg) = 50
by_file(ctg) = TRUE
newctg = catalog_retile(ctg, "path/to/new/catalog")

# Being flexible this function can also compress a catalog but this is
# not really useful since laszip from LAStools is a free and open source
# program.

buffer(ctg) = 0
by_file(ctg) = TRUE
newctg = catalog_retile(ctg, "path/to/compressed/file",  ext = "laz")
# }