filters function

Filter points of interest

Filter points of interest (POI) from a LAS object where conditions are true.

filter_poi(las, ...)

filter_first(las)

filter_firstlast(las)

filter_firstofmany(las)

filter_ground(las)

filter_last(las)

filter_nth(las, n)

filter_single(las)

filter_duplicates(las)

## S3 method for class 'LAS'
filter_duplicates(las)

## S3 method for class 'LAScatalog'
filter_duplicates(las)

Arguments

• las: An object of class LAS
• ...: Logical predicates. Multiple conditions are combined with '&' or ','
• n: integer ReturnNumber == n

Returns

An object of class LAS

Details

• filter_poi Select points of interest based on custom logical criteria.
• filter_first Select only the first returns.
• filter_firstlast Select only the first and last returns.
• filter_ground Select only the returns classified as ground according to LAS specification.
• filter_last Select only the last returns i.e. the last returns and the single returns.
• filter_nth Select the returns from their position in the return sequence.
• filter_firstofmany Select only the first returns from pulses which returned multiple points.
• filter_single Select only the returns that return only one point.
• filter_duplicates Removes the duplicated points (duplicated by XYZ)

Non-supported LAScatalog options

The option select is not supported and not respected because it always preserves the file format and all the attributes. select = "*" is imposed internally.

Examples

LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
lidar = readLAS(LASfile)

# Select the first returns classified as ground
firstground = filter_poi(lidar, Classification == 2L & ReturnNumber == 1L)

# Multiple arguments are equivalent to &
firstground = filter_poi(lidar, Classification == 2L, ReturnNumber == 1L)

# Multiple criteria
first_or_ground = filter_poi(lidar, Classification == 2L | ReturnNumber == 1L)