Digital Surface Model Algorithm
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.
dsmtin(max_edge = 0, highest = TRUE)
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.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) ## Not run: # 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) ## End(Not run)
Other digital surface model algorithms: dsm_pitfree, dsm_point2raster