Filter to first acquisition from multi-temporal tiles

Identifies tiles with multiple acquisitions and returns only the first (earliest) acquisition for each tile as a filtered VPC.

Usage

filter_first(
  path,
  entire_tiles = TRUE,
  tolerance = 1,
  multitemporal_only = FALSE,
  verbose = TRUE
)

Arguments

path

Character vector of input paths, a VPC file path, or a VPC object already loaded in R. Can be a mix of LAS/LAZ/COPC files and .vpc files.

entire_tiles

Logical. If TRUE (default), only considers tiles where the entire tile area has multi-temporal coverage. If FALSE, includes tiles with partial multi-temporal coverage.

tolerance

Numeric. Tolerance in coordinate units for snapping extents to grid (default: 1, submeter inaccuracies are ignored). If > 0, coordinates within this distance of a grid line will be snapped before processing. Set to 0 to disable snapping.

multitemporal_only

Logical. If TRUE, only returns tiles with multiple acquisitions. If FALSE (default), includes all tiles.

verbose

Logical. If TRUE (default), prints information about filtering results.

Value

A VPC object (list) containing only the first acquisition for each tile. Returns NULL invisibly if no features match the filter.

Details

The function performs the following steps:

1. Resolves input paths to a VPC object

2. Analyzes tiles for multi-temporal coverage

3. Groups tiles by location and selects the earliest acquisition for each

4. Returns a filtered VPC object

See also

filter_latest, filter_spatial, filter_multitemporal, resolve_vpc

Examples

f <- system.file("extdata", package = "managelidar")

# get first acquisition per tile (entire tiles only, with 10m tolerance)
vpc <- filter_first(f, tolerance = 10)
#> Error in loadNamespace(x): there is no package called ‘lasR’