Pywayne Cv Geometric Hull Calculator

Geometric hull calculator for 2D point sets supporting convex hull, concave hull (concave-hull, alphashape), and minimum bounding rectangle. Use when working with pywayne.cv.geometric_hull_calculator module to compute geometric hulls, visualize results with OpenCV or matplotlib, and generate random test point sets.

Pywayne Geometric Hull Calculator

This module computes geometric hulls (convex and concave) for 2D point sets.

Quick Start

python

from pywayne.cv.geometric_hull_calculator import GeometricHullCalculator
import numpy as np

# Create calculator with random points
points = GeometricHullCalculator.generate_random_points(num_points=50)
calculator = GeometricHullCalculator(points, algorithm='concave-hull')

# Get results
print(f"MBR: {calculator.get_mbr()}")
print(f"Convex Hull: {calculator.get_convex_hull()}")
print(f"Concave Hull: {calculator.get_concave_hull()}")

# Visualize with matplotlib
calculator.visualize_matplotlib()

Initialization

python

# algorithm options: 'concave-hull' or 'alphashape'
# use_filtered_pts: Enable point filtering based on radius
calculator = GeometricHullCalculator(
    points=your_points,
    algorithm='alphashape',
    use_filtered_pts=True
)

Supported Algorithms

Algorithm	Description
concave-hull	Concave hull using concave_hull library
alphashape	Concave hull using alphashape library

Hull Types

Type	Method	Description
Convex Hull	get_convex_hull()	Outer hull containing all points
Concave Hull	get_concave_hull()	Inner concave boundary

Properties

Property	Description
points	Input 2D points (N×2 numpy array)
algorithm	Algorithm used for concave hull
use_filtered_pts	Whether filtered points were used
box	Minimum Bounding Rectangle corners
center	Center point of input points
filter_radius	Radius used for point filtering
concave_hull_result	Concave hull points or polygons

Visualization

OpenCV Visualization

python

calculator.visualize_opencv()

Displays: All input points, MBR, center, filter circle (if enabled), concave hull (green), convex hull (red).

Matplotlib Visualization

python

calculator.visualize_matplotlib()

Displays: All input points (red), MBR (blue), center, filter radius circle (if enabled), concave hull (orange), convex hull (purple).

Requirements

• numpy - Array operations
• cv2 (OpenCV) - For OpenCV visualization and MBR computation
• matplotlib - For matplotlib visualization
• scipy - For convex hull computation
• concave_hull - Concave hull algorithm
• alphashape - Alphashape algorithm
• shapely - Polygon operations for area calculation

Notes

• Point filtering uses radius = 30% of shorter MBR edge length
• MBR computed using OpenCV's minAreaRect
• Convex hull uses scipy's ConvexHull
• Supports both single Polygon and MultiPolygon from alphashape results