Struct AlphaShape 

pub struct AlphaShape { /* private fields */ }

Alpha shape of a point set

An alpha shape is a generalization of convex hull that can represent non-convex boundaries. It is parametrized by α which controls the level of detail.

Implementations

impl AlphaShape

pub fn new(points: &Array2<f64>, alpha: f64) -> SpatialResult<Self>

Create a new alpha shape

Arguments

• points - The points to compute alpha shape for, shape (npoints, ndim)
• alpha - The alpha parameter (≥ 0)

Returns

• A new AlphaShape instance or an error

Examples

use scirs2_spatial::alphashapes::AlphaShape;
use scirs2_core::ndarray::array;

let points = array![
    [0.0, 0.0],
    [1.0, 0.0],
    [1.0, 1.0],
    [0.0, 1.0]
];

let alphashape = AlphaShape::new(&points, 1.0).expect("Operation failed");
let boundary = alphashape.boundary();
println!("Boundary: {:?}", boundary);

pub fn multi_alpha( points: &Array2<f64>, alphas: &[f64], ) -> SpatialResult<Vec<Self>>

Compute alpha shape for multiple alpha values efficiently

Arguments

• points - The points to compute alpha shapes for
• alphas - Vector of alpha values to compute

Returns

• Vector of alpha shapes corresponding to each alpha value

Examples

use scirs2_spatial::alphashapes::AlphaShape;
use scirs2_core::ndarray::array;

let points = array![
    [0.0, 0.0],
    [1.0, 0.0],
    [1.0, 1.0],
    [0.0, 1.0],
    [0.5, 0.5]
];

let alphas = vec![0.5, 1.0, 2.0];
let shapes = AlphaShape::multi_alpha(&points, &alphas).expect("Operation failed");

for (i, shape) in shapes.iter().enumerate() {
    println!("Alpha {}: {} boundary elements", alphas[i], shape.boundary().len());
}

pub fn alpha(&self) -> f64

Get the alpha parameter

pub fn points(&self) -> &Array2<f64>

Get the input points

pub fn ndim(&self) -> usize

Get the dimension

pub fn npoints(&self) -> usize

Get the number of points

pub fn complex(&self) -> &[Vec<usize>]

Get the alpha complex (all included simplices)

Returns

• Vector of simplices in the alpha complex

pub fn boundary(&self) -> &[Vec<usize>]

Get the boundary of the alpha shape

Returns

• Vector of boundary faces (edges in 2D, triangles in 3D)

pub fn circumradii(&self) -> &[f64]

Get the circumradii of all simplices

pub fn delaunay(&self) -> &Delaunay

Get the underlying Delaunay triangulation

pub fn measure(&self) -> SpatialResult<f64>

Compute the area (2D) or volume (3D) of the alpha shape

Returns

• The area/volume of the alpha shape

pub fn find_optimal_alpha( points: &Array2<f64>, criterion: &str, ) -> SpatialResult<(f64, Self)>

Find optimal alpha value using the alpha spectrum

Arguments

• points - Input points
• criterion - Optimization criterion (“area”, “volume”, “boundary”)

Returns

• Optimal alpha value and corresponding alpha shape

Examples

use scirs2_spatial::alphashapes::AlphaShape;
use scirs2_core::ndarray::array;

let points = array![
    [0.0, 0.0],
    [1.0, 0.0],
    [1.0, 1.0],
    [0.0, 1.0],
    [0.5, 0.5]
];

let (optimal_alpha, shape) = AlphaShape::find_optimal_alpha(&points, "area").expect("Operation failed");
println!("Optimal alpha: {}", optimal_alpha);

Trait Implementations

impl Clone for AlphaShape

fn clone(&self) -> AlphaShape

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AlphaShape

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.