我正在尝试使用以下代码来计算两个对象的外接半径和内接半径。我使用了script的inscribedRadius参数,使用了外接的半径function
我不明白为什么我得到的内接半径大于外接半径。知道有什么问题吗?以及如何解决?
代码:
clc;
clear;
RGB = imcomplement(imread('https://i.stack.imgur.com/8WLAt.jpg'));
I = rgb2gray(RGB);
bw = imbinarize(I);
bw = imfill(bw,'holes');
imshow(bw)
hold on;
[B,L] = bwboundaries(bw,'noholes');
stats = regionprops(L,'Centroid','MajorAxisLength');
for i = 1 : numel(stats)
b = B{i};
c = stats(i).Centroid;
y = b(:,1);
x = b(:,2);
plot( b(:,2),b(:,1),'Color','red','linewidth',2);
text(c(1),c(2),num2str(i),'Color','red');
xMin = min(x);
xMax = max(x);
yMin = min(y);
yMax = max(y);
scalingFactor = 1000 / min([xMax-xMin, yMax-yMin]);
x2s = (x - xMin) * scalingFactor + 1;
y2s = (y - yMin) * scalingFactor + 1;
mask = poly2mask(x2s, y2s, ceil(max(y2s)), ceil(max(x2s)));
edtImage = bwdist(~mask);
inscribedRadius = max(edtImage(:));
[yCenter, xCenter] = find(edtImage == inscribedRadius);
xCenter = (xCenter - 1)/ scalingFactor + xMin;
yCenter = (yCenter - 1)/ scalingFactor + yMin;
inscribedRadius = inscribedRadius / scalingFactor
[circumscribedCenter,circumscribedRadius] = minboundcircle(x,y); % from https://www.mathworks.com/matlabcentral/fileexchange/34767-a-suite-of-minimal-bounding-objects?focused=3820656&tab=function
circumscribedRadius
end
结果是:
inscribedRadius
= 264,cumscribedRadius
= 186.6762inscribedRadius
= 130.4079,circumscribedRadius
= 132.3831对象1(框)的值错误,因为inscribedRadius
不能大于cumscribedRadius
。它们适用于对象2(圆圈)
[如果您查看mask
图像,您会注意到绘制的正方形触摸了图像的右边缘和下边缘。仅在形状的左侧和顶部有背景。距离变换bwdist(~mask)
随后为形状内的每个像素计算到背景的距离,但是由于背景仅在左边和顶部,因此在形状右下角的像素的距离为1000,而不是1。距离变换应该在中间有一个最大值,该点至少与三个最近的形状边缘点等距。
解决方案很简单:poly2mask
必须创建一个宽一像素高的图像:
mask = poly2mask(x2s, y2s, ceil(max(y2s)) + 1, ceil(max(x2s)) + 1); ^^^ ^^^
与预期的一样,平方的计算出的
inscribedRadius
为132。