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Simulating Crook Deformations

Overview

This vignette shows how to apply crook deformations to LiDAR-derived stem point clouds using {crookR} (deformation-only).

library(crookR)
data("example_stem")

Example: XYZ point cloud for a single stem


library(crookR)
data("example_stem")
str(example_stem)
#> Classes 'data.table' and 'data.frame':   708145 obs. of  3 variables:
#>  $ X: num  0.28 0.28 0.28 0.28 0.28 ...
#>  $ Y: num  0.28 0.28 0.28 0.28 0.28 ...
#>  $ Z: num  0.01 0.01 0.02 0.02 0.02 ...
#>  - attr(*, ".internal.selfref")=<externalptr>
head(example_stem)
#>        X     Y     Z
#>    <num> <num> <num>
#> 1:  0.28  0.28  0.01
#> 2:  0.28  0.28  0.01
#> 3:  0.28  0.28  0.02
#> 4:  0.28  0.28  0.02
#> 5:  0.28  0.28  0.02
#> 6:  0.26  0.26  0.00

Single-direction deformation (krok_type = “1dir”)

A smooth lateral deviation of amplitude krok_deviation is applied over a vertical range of length krok_length, starting at krok_start.

stem_1dir <- crook_deform(
  x = example_stem,
  krok_length     = 0.5,
  krok_start      = 4.0,
  krok_type       = "1dir", 
  krok_deviation  = 0.08,   # try 0.05..0.12 for milder/stronger bends
  az              = 0,      # bend along +X
  spar            = 0.8
)

# Quick plan-view check

op <- par(mfrow = c(1,2), mar = c(3,3,2,1))
plot(example_stem$X, example_stem$Z, pch=16, cex=0.3, xlab="X (m)", ylab="Z (m)", main="Original")
plot(stem_1dir$X,     stem_1dir$Z,     pch=16, cex=0.3, xlab="X (m)", ylab="Z (m)", main="Crooked 1dir (az = 0°)")

par(op)

Double-direction deformation (krok_type = “2dir”) with inflection

The deviation changes direction at a fraction inflektion_X of the length (0 < inflektion_X < 1). inflektion_ext scales the amplitude after the inflection.

stem_2dir <- crook_deform( 
  x = example_stem,
  krok_length = 0.5,
  krok_start = 4.0,
  krok_type = "2dir",
  krok_deviation = 0.1,
  inflektion_X = 1/3,    # inflection at ~33% of the deformed length
  inflektion_ext = 1/2,    # second leg amplitude relative to first
  az = 0,     
  spar = 0.8
  )

op <- par(mfrow = c(1,2), mar = c(3,3,2,1))
plot(example_stem$X, example_stem$Z, pch=16, cex=0.3, xlab="X (m)", ylab="Z (m)", main="Original")
plot(stem_2dir$X,     stem_2dir$Z,     pch=16, cex=0.3, xlab="X (m)", ylab="Z (m)", main="Crooked 2dir (ip = 0.33)")

par(op)

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.