Pits and spikes filling for raster. Typically used for post-processing CHM. This algorithm is from St-Onge 2008 (see reference).
Usage
pit_fill(
raster,
lap_size = 3L,
thr_lap = 0.1,
thr_spk = -0.1,
med_size = 3L,
dil_radius = 0L,
ofile = temptif()
)Arguments
- raster
LASRalgorithm. A stage that produces a raster.
- lap_size
integer. Size of the Laplacian filter kernel (integer value, in pixels).
- thr_lap
numeric. Threshold Laplacian value for detecting a cavity (all values above this value will be considered a cavity). A positive value.
- thr_spk
numeric. Threshold Laplacian value for detecting a spike (all values below this value will be considered a spike). A negative value.
- med_size
integer. Size of the median filter kernel (integer value, in pixels).
- dil_radius
integer. Dilation radius (integer value, in pixels).
- ofile
character. Full outputs are always stored on disk. If
ofile = ""then the stage will not store the result on disk and will return nothing. It will however hold partial output results temporarily in memory. This is useful for stage that are only intermediate stage.
References
St-Onge, B., 2008. Methods for improving the quality of a true orthomosaic of Vexcel UltraCam images created using alidar digital surface model, Proceedings of the Silvilaser 2008, Edinburgh, 555-562. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=81365288221f3ac34b51a82e2cfed8d58defb10e
Examples
f <- system.file("extdata", "MixedConifer.las", package="lasR")
reader <- reader_las(filter = keep_first())
tri <- triangulate()
chm <- rasterize(0.25, tri)
pit <- pit_fill(chm)
u <- exec(reader + tri + chm + pit, on = f)
chm <- u[[1]]
sto <- u[[2]]
#terra::plot(c(chm, sto), col = lidR::height.colors(25))