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3D matching of detected tree top positions with reference positions

tree_matching.Rd

First computes a matching index for each potential pair associating a detected with a reference tree. This index is the 3D distance between detected and reference points, divided by a maximum matching distance set by user-defined parameters. Pairs with the lowest index are then iteratively associated.

Usage

tree_matching(lr, ld, delta_ground = 2.1, h_prec = 0.14, stat = TRUE)

Arguments

lr

data.frame or matrix. 3D coordinates (X Y Height) of reference positions

ld

data.frame or matrix. 3D coordinates (X Y Height) of detected positions

delta_ground

numeric. buffer around trunk position : absolute value

h_prec

numeric. buffer around apex position : proportion of reference tree height

stat

boolean. should matching stats be computed

Value

A data.frame with matched pairs (row of reference positions in first column, and row of detected positions in second column) and corresponding 3D distances

References

Monnet, J.-M. 2011. Using airborne laser scanning for mountain forests mapping: Support vector regression for stand parameters estimation and unsupervised training for treetop detection. Ph.D. thesis. University of Grenoble, France. pp. 53-55 https://theses.hal.science/tel-00652698/document

Monnet, J.-M., Mermin, E., Chanussot, J., Berger, F. 2010. Tree top detection using local maxima filtering: a parameter sensitivity analysis. Silvilaser 2010, the 10th International Conference on LiDAR Applications for Assessing Forest Ecosystems, September 14-17, Freiburg, Germany, 9 p. https://hal.science/hal-00523245/document

See also

plot_matched, hist_detection

Examples

# create reference and detected trees
ref_trees <- cbind(c(1, 4, 3, 4, 2), c(1, 1, 2, 3, 4), c(15, 18, 20, 10, 11))
def_trees <- cbind(c(2, 2, 4, 4), c(1, 3, 4, 1), c(16, 19, 9, 15))
#
# match trees
match1 <- tree_matching(ref_trees, def_trees)
match2 <- tree_matching(ref_trees, def_trees, delta_ground = 2, h_prec = 0)
match1
#>   r d h_diff plan_diff
#> 1 1 1      1  1.000000
#> 2 3 2     -1  1.414214
#> 3 4 3     -1  1.000000
#> 4 2 4     -3  0.000000
match2
#>   r d h_diff plan_diff
#> 1 1 1      1  1.000000
#> 2 4 3     -1  1.000000
#> 3 3 2     -1  1.414214

# 2D display of matching result
plot_matched(ref_trees, def_trees, match1, xlab = "X", ylab = "Y")

plot_matched(ref_trees, def_trees, match2, xlab = "X", ylab = "Y")