如何使用 C# 識別 2D 點雲中的凸孔並將其多邊形化？

此程式碼示範了一種在一組 2d 點中尋找凸孔的方法。此方法包括建立點雲位圖、計算位圖中每個單元的資料密度、建立未使用區域的清單（map[][] = 0 或map[][]

這是此演算法的 C# 實作提供：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Drawing;

namespace HoleFinder
{
    class Program
    {
        // Define a cell structure for the bitmap
        public struct Cell
        {
            public double x0, x1, y0, y1; // Bounding box of points inside the cell
            public int count;            // Number of points inside the cell
        }

        // Define a line structure for representing hole boundaries
        public struct Line
        {
            public double x0, y0, x1, y1; // Line edge points
            public int id;             // Id of the hole to which the line belongs for segmentation/polygonization
            public int i0, i1, j0, j1;    // Index in map[][]
        }

        // Compute the bounding box of the point cloud
        public static (double x0, double x1, double y0, double y1) ComputeBoundingBox(List<point> points)
        {
            double x0 = points[0].X;
            double x1 = points[0].X;
            double y0 = points[0].Y;
            double y1 = points[0].Y;

            foreach (var point in points)
            {
                if (point.X  x1) x1 = point.X;
                if (point.Y  y1) y1 = point.Y;
            }

            return (x0, x1, y0, y1);
        }

        // Create a bitmap of the point cloud
        public static int[,] CreateBitmap(List<point> points, (double x0, double x1, double y0, double y1) boundingBox, int N)
        {
            // Create a 2D array to represent the bitmap
            int[,] bitmap = new int[N, N];

            // Compute the scale factors for converting point coordinates to bitmap indices
            double mx = N / (boundingBox.x1 - boundingBox.x0);
            double my = N / (boundingBox.y1 - boundingBox.y0);

            // Iterate over the points and increment the corresponding cells in the bitmap
            foreach (var point in points)
            {
                int i = (int)Math.Round((point.X - boundingBox.x0) * mx);
                int j = (int)Math.Round((point.Y - boundingBox.y0) * my);

                if (i >= 0 && i = 0 && j  FindUnusedAreasHorizontalVertical(Cell[] map, int N, int treshold = 0)
        {
            List unusedAreas = new List();

            // Scan horizontally
            for (int j = 0; j = 0)
                        {
                            unusedAreas.Add((i0, i1, j, j));
                            i0 = -1;
                            i1 = -1;
                        }
                    }
                }

                if (i0 >= 0) unusedAreas.Add((i0, i1, j, j));
            }

            // Scan vertically
            for (int i = 0; i = 0)
                        {
                            unusedAreas.Add((i, i, j0, j1));
                            j0 = -1;
                            j1 = -1;
                        }
                    }
                }

                if (j0 >= 0) unusedAreas.Add((i, i, j0, j1));
            }

            return unusedAreas;
        }

        // Segment the list of unused areas into groups of connected components
        public static List<list i0 int i1 j0 j1>> SegmentUnusedAreas(List unusedAreas)
        {
            // Initialize each unused area as a separate group
            List<list i0 int i1 j0 j1>> segments = new List<list i0 int i1 j0 j1>>();
            foreach (var unusedArea in unusedAreas)
            {
                segments.Add(new List { unusedArea });
            }

            // Iterate until no more segments can be joined
            bool joined = true;
            while (joined)
            {
                joined = false;

                // Check if any two segments intersect or are adjacent
                for (int i = 0; i = unusedArea2.i0
                                    && unusedArea1.j0 = unusedArea2.j0)
                                {
                                    intersects = true;
                                    break;
                                }
                            }

                            if (intersects) break;
                        }

                        // Check for adjacency
                        bool adjacent = false;
                        if (!intersects)
                        {
                            foreach (var unusedArea1 in segments[i])
                            {
                                foreach (var unusedArea2 in segments[j])
                                {
                                    if (unusedArea1.i0 == unusedArea2.i0 && unusedArea1.i1 == unusedArea2.i1
                                        && ((unusedArea1.j1 == unusedArea2.j0 && Math.Abs(unusedArea1.j0 - unusedArea2.j1) == 1)
                                            || (unusedArea1.j0 == unusedArea2.j1 && Math.Abs(unusedArea1.j1 - unusedArea2.j0) == 1)))
                                    {
                                        adjacent = true;
                                        break;
                                    }

                                    if (unusedArea1.j0 == unusedArea2.j0 && unusedArea1.j1 == unusedArea2.j1</list></list></list></point></point>

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