components_ashape3d: Connected subsets computation
In tlafarge/alphashape3d: Implementation of the 3D Alpha-Shape for the Reconstruction of 3D Sets from a Point Cloud
Description
Usage
Arguments
Details
Value
See Also
Examples
Description
This function calculates and clusters the different connected components of
the α-shape of a given sample of points in the three-dimensional
space.
Usage
1
components_ashape3d(as3d, indexAlpha = 1)
Arguments
as3d
An object of class "ashape3d" that represents the
α-shape of a given sample of points in the three-dimensional
space, see ashape3d.
indexAlpha
A single value or vector with the indexes of
as3d$alpha that should be used for the computation, see Details.
Details
The function components_ashape3d computes the connected components of
the α-shape for each value of α in
as3d$alpha[indexAlpha] when indexAlpha is numeric.
If indexAlpha="all" or indexAlpha="ALL" then the function
computes the connected components of the α-shape for all values
of α in as3d$alpha.
Value
If indexAlpha is a single value then the function returns a
vector v of length equal to the sample size. For each sample point
i, v[i] represents the label of the connected component to
which the point belongs (for isolated points, v[i]=-1). The labels of
the connected components are ordered by size where the largest one (in
number of vertices) gets the smallest label which is one.
Otherwise components_ashape3d returns a list of vectors describing
the connected components of the α-shape for each selected value
of α.
See Also
Examples
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T1 <- rtorus(1000, 0.5, 2)
T2 <- rtorus(1000, 0.5, 2, ct = c(2, 0, 0), rotx = pi/2)
x <- rbind(T1, T2)
alpha <- c(0.25, 2)
ashape3d.obj <- ashape3d(x, alpha = alpha)
plot(ashape3d.obj, indexAlpha = "all")
# Connected components of the alpha-shape for both values of alpha
comp <- components_ashape3d(ashape3d.obj, indexAlpha = "all")
class(comp)
# Number of components and points in each component for alpha=0.25
table(comp[[1]])
# Number of components and points in each component for alpha=2
table(comp[[2]])
# Plot the connected components for alpha=0.25
plot(ashape3d.obj, byComponents = TRUE, indexAlpha = 1)
tlafarge/alphashape3d documentation built on May 31, 2019, 3:48 p.m.
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Description Usage Arguments Details Value See Also Examples
Description
This function calculates and clusters the different connected components of the α-shape of a given sample of points in the three-dimensional space.
Usage
1 | components_ashape3d(as3d, indexAlpha = 1)
|
Arguments
as3d |
An object of class |
indexAlpha |
A single value or vector with the indexes of
|
Details
The function components_ashape3d computes the connected components of
the α-shape for each value of α in
as3d$alpha[indexAlpha] when indexAlpha is numeric.
If indexAlpha="all" or indexAlpha="ALL" then the function
computes the connected components of the α-shape for all values
of α in as3d$alpha.
Value
If indexAlpha is a single value then the function returns a
vector v of length equal to the sample size. For each sample point
i, v[i] represents the label of the connected component to
which the point belongs (for isolated points, v[i]=-1). The labels of
the connected components are ordered by size where the largest one (in
number of vertices) gets the smallest label which is one.
Otherwise components_ashape3d returns a list of vectors describing
the connected components of the α-shape for each selected value
of α.
See Also
Examples
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | T1 <- rtorus(1000, 0.5, 2)
T2 <- rtorus(1000, 0.5, 2, ct = c(2, 0, 0), rotx = pi/2)
x <- rbind(T1, T2)
alpha <- c(0.25, 2)
ashape3d.obj <- ashape3d(x, alpha = alpha)
plot(ashape3d.obj, indexAlpha = "all")
# Connected components of the alpha-shape for both values of alpha
comp <- components_ashape3d(ashape3d.obj, indexAlpha = "all")
class(comp)
# Number of components and points in each component for alpha=0.25
table(comp[[1]])
# Number of components and points in each component for alpha=2
table(comp[[2]])
# Plot the connected components for alpha=0.25
plot(ashape3d.obj, byComponents = TRUE, indexAlpha = 1)
|
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