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Get the temporal extent of LASfiles

Source: R/get_temporal_extent.R
get_temporal_extent.Rd

Extracts the temporal extent (acquisition dates) from LASfiles. Can return dates per file or the combined date range of all files.

Usage

get_temporal_extent(
  path,
  per_file = TRUE,
  full.names = FALSE,
  from_csv = NULL,
  return_referenceyear = FALSE,
  fix_false_gpstime = TRUE,
  verbose = TRUE
)

Arguments

path

Character. Path to a LAS/LAZ/COPC file, a directory, or a Virtual Point Cloud (.vpc) referencing these files.

per_file

Logical. If TRUE (default), returns dates per file. If FALSE, returns combined date range of all files.

full.names

Logical. If TRUE, filenames in the output are full paths; otherwise base filenames (default). Only used when per_file = TRUE.

from_csv

Character or NULL. If provided, path to a CSV file containing acquisition dates for tiles without GPS time. The CSV must have columns minx, miny (tile coordinates in km) and date (YYYY-MM-DD). If NULL (default), dates for non-GPS tiles are extracted from file headers.

return_referenceyear

Logical. If TRUE, returns the reference year instead of the acquisition date (e.g., reference year 2015 for data acquired in November or December 2014). Default is FALSE.

fix_false_gpstime

Logical. If TRUE (default), detects files that claim GPS time encoding in their header but contain week-second timestamps instead of standard GPS time. Such files produce spurious dates in the range 2011-09-14 to 2011-09-21 when decoded as GPS time. Affected files are silently reclassified as non-GPS and their dates are resolved via CSV or header fallback instead.

verbose

Logical. If TRUE (default), prints temporal extent information.

Value

When per_file = TRUE: A data.frame with columns:

filename

Filename of the LASfile.

date

Acquisition date (Date object) or reference year (numeric) if return_referenceyear = TRUE.

date_source

Character. One of data (files with valid GPStime), csv (matched from CSV file), or header (from file header).

When per_file = FALSE: A single-row data.frame with start and end (Date objects or numeric years depending on return_referenceyear).

Details

For LAS 1.3+ files with GPS time encoding, the function extracts the date from the first point. For older files without GPS time, if from_csv is provided, the function assigns the closest acquisition date prior to the processing date from the CSV file based on tile coordinates. Otherwise, the date is extracted from the LAS header (processing date).

When return_referenceyear = TRUE, November and December acquisitions are shifted to the following year to standardize reference years.

See also

get_spatial_extent, filter_temporal

Examples

folder <- system.file("extdata", package = "managelidar")
las_files <- list.files(folder, full.names = TRUE, pattern = "*.laz")

# Get dates per file
las_files |> get_temporal_extent()
#> Error in loadNamespace(x): there is no package called ‘lasR’

# Get combined date range
las_files |> get_temporal_extent(per_file = FALSE)
#> Error in loadNamespace(x): there is no package called ‘lasR’

# Get reference years
las_files |> get_temporal_extent(return_referenceyear = TRUE)
#> Error in loadNamespace(x): there is no package called ‘lasR’

# Using CSV for reference dates
csv_path <- system.file("extdata", "acquisition_dates.csv", package = "managelidar")
get_temporal_extent(folder, from_csv = csv_path)
#> Error in loadNamespace(x): there is no package called ‘lasR’