Test of the inside of an α-shape
This function checks whether points are inside an α-shape.
inashape3d(as3d, indexAlpha = 1, points)
as3d |
An object of class |
indexAlpha |
A single value or vector with the indexes of
|
points |
A 3-column matrix with the coordinates of the input points. |
The function inashape3d checks whether each point in points is
inside the α-shape for each value of α in
as3d$alpha[indexAlpha].
If indexAlpha="all" or indexAlpha="ALL" then the function
checks whether each point in points is inside the α-shape
for all values of α in as3d$alpha.
If indexAlpha is a single value then the function returns a
vector of boolean of length the number of input points. The element at
position i is TRUE if the point in points[i,] is inside
the α-shape.
Otherwise inashape3d returns a list of vectors of boolean values
(each object in the list as described above).
T1 <- rtorus(2000, 0.5, 2) T2 <- rtorus(2000, 0.5, 2, ct = c(2, 0, 0), rotx = pi/2) x <- rbind(T1, T2) ashape3d.obj <- ashape3d(x, alpha = 0.4) # Random sample of points in a plane points <- matrix(c(5*runif(10000) - 2.5, rep(0.01, 5000)), nc = 3) in3d <- inashape3d(ashape3d.obj, points = points) plot(ashape3d.obj, transparency = 0.2) colors <- ifelse(in3d, "blue", "green") rgl.points(points, col = colors)
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