霍夫峰检测

Question

我已经实现了霍夫峰检测。输出结果如下：

我们可以看到红线与canvas的两侧（左、右）相交。

如何限制源代码行之间检测到的行的长度？

例如，

。

源代码

public class Line
{
    public Point Start { get; set; }
    public Point End { get; set; }

    public Line(Point start, Point end)
    {
        Start = start;
        End = end;
    }
}

public class HoughLineTransform
{
    public HoughMap Accumulator { get; set; }

    public HoughLineTransform()
    {
    }

    public List<Line> GetLines(int threshold)
    {
        if (Accumulator == null)
        {
            throw new Exception("HoughMap is null");
        }

        int houghWidth = Accumulator.Width;
        int houghHeight = Accumulator.Height;
        int imageWidth = Accumulator.Image.Width;
        int imageHeight = Accumulator.Image.Height;

        List<Line> lines = new List<Line>();

        if (Accumulator == null)
            return lines;

        for (int rho = 0; rho < houghWidth; rho++)
        {
            for (int theta = 0; theta < houghHeight; theta++)
            {
                if ((int)Accumulator[rho, theta] >= threshold)
                {
                    int peak = Accumulator[rho, theta];

                    for (int ly = -4; ly <= 4; ly++)
                    {
                        for (int lx = -4; lx <= 4; lx++)
                        {
                            if ((ly + rho >= 0 && ly + rho < houghWidth) && (lx + theta >= 0 && lx + theta < houghHeight))
                            {
                                if ((int)Accumulator[rho + ly, theta + lx] > peak)
                                {
                                    peak = Accumulator[rho + ly, theta + lx];
                                    ly = lx = 5;
                                }
                            }
                        }
                    }

                    if (peak > (int)Accumulator[rho, theta])
                        continue;

                    int x1, y1, x2, y2;
                    x1 = y1 = x2 = y2 = 0;

                    double rad = theta * Math.PI / 180;

                    if (theta >= 45 && theta <= 135)
                    {
                        x1 = 0;
                        y1 = (int)(((double)(rho - (houghWidth / 2)) - ((x1 - (imageWidth / 2)) * Math.Cos(rad))) / Math.Sin(rad) + (imageHeight / 2));
                        x2 = imageWidth - 0;
                        y2 = (int)(((double)(rho - (houghWidth / 2)) - ((x2 - (imageWidth / 2)) * Math.Cos(rad))) / Math.Sin(rad) + (imageHeight / 2));
                    }
                    else
                    {
                        y1 = 0;
                        x1 = (int)(((double)(rho - (houghWidth / 2)) - ((y1 - (imageHeight / 2)) * Math.Sin(rad))) / Math.Cos(rad) + (imageWidth / 2));
                        y2 = imageHeight - 0;
                        x2 = (int)(((double)(rho - (houghWidth / 2)) - ((y2 - (imageHeight / 2)) * Math.Sin(rad))) / Math.Cos(rad) + (imageWidth / 2));
                    }

                    lines.Add(new Line(new Point(x1, y1), new Point(x2, y2)));
                }
            }
        }

        return lines;
    }
}

^Related:

Answer 1

一种简单的方法是在原始图像上叠加生成的 houghlines 并检查像素重叠的位置（具有一定的 window）。

如果它们开始或结束重叠，则您有线段的开始/结束。

顺便说一句：我没有检查过你的算法，但我在大约 15 年前自己写了一个。我记得有一种迭代方法，你一次找到一条线（只是累积图像中的最大值）。找到一条线后，删除该线的累积像素，然后通过找到最大值重新开始。然后找到第二重要的行。等等。

霍夫峰检测

Hough Peak detection

c#

image-processing

hough-transform