lidR (version 4.1.2)

dsm_tin: Digital Surface Model Algorithm

Description

This function is made to be used in rasterize_canopy. It implements an algorithm for digital surface model computation using a Delaunay triangulation of first returns with a linear interpolation within each triangle.

Usage

dsmtin(max_edge = 0, highest = TRUE)

Arguments

max_edge

numeric. Maximum edge length of a triangle in the Delaunay triangulation. If a triangle has an edge length greater than this value it will be removed to trim dummy interpolation on non-convex areas. If max_edge = 0 no trimming is done (see examples).

highest

bool. By default it keeps only the highest point per pixel before to triangulate to decrease computation time. If highest = FALSE all first returns are used.

See Also

Other digital surface model algorithms: dsm_pitfree, dsm_point2raster

Examples

LASfile <- system.file("extdata", "MixedConifer.laz", package="lidR")
las <- readLAS(LASfile)
col <- height.colors(50)

# Basic triangulation and rasterization of first returns
chm <- rasterize_canopy(las, res = 1, dsmtin())
plot(chm, col = col)

if (FALSE) {
# Potentially complex concave subset of point cloud
x = c(481340, 481340, 481280, 481300, 481280, 481340)
y = c(3812940, 3813000, 3813000, 3812960, 3812940, 3812940)
las2 = clip_polygon(las,x,y)
plot(las2)

# Because the TIN interpolation is done within the convex hull of the point cloud
# dummy pixels are interpolated that are correct according to the interpolation method
# used, but meaningless in our CHM
chm <- rasterize_canopy(las2, res = 0.5, dsmtin())
plot(chm, col = col)

# Use 'max_edge' to trim dummy triangles
chm = rasterize_canopy(las2, res = 0.5, dsmtin(max_edge = 3))
plot(chm, col = col)
}