How to find the nearest object to a reference point in binary image?

Question

Meshooo 2014-11-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/162892-how-to-find-the-nearest-object-to-a-reference-point-in-binary-image

评论： Image Analyst 2014-11-16

Dear all,

I have a binary image that contains two objects(Object_A, Object_B) very close to each other as shown below. I want to find which object is closer to a reference point in order to be selected (Object_B in this example).

I was thinking to find the distance of the centroid of each object to the reference point (in this example the centroid of the reference point X = 360, Y = 330), but this will not work because in few cases the centroid of the far object could be closer to the reference point as I tried to explain in the figure below.

Is there any way to find the closest object to a reference point?

Any help and suggestion will be appreciated.

Meshoo

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Image Analyst 2014-11-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/162892-how-to-find-the-nearest-object-to-a-reference-point-in-binary-image#answer_159119

在 MATLAB Online 中打开

It's trivial. Just use bwboundaries to get the list of (x,y) coordinates of the boundary and then put in a for loop, calculating the distance using the Pythagorean Theorem to get the boundary that is the closest. In the for loop, you can vectorize it and use min().

boundaries = bwboundaries(binaryImage);
overallMinDistance = inf;
for b = 1 : length(boundaries)
   thisBoundaryX = boundaries{b}(:, 1);
   thisBoundaryY = boundaries{b}(:, 2);
   distances = sqrt((thisBoundaryX - refx).^2 + (thisBoundaryY - refy).^2);
   [minDistance, indexOfMin] = min(distances);
   if minDistance < overallMinDistance
      % This boundary is the closer one.
.............you finish the rest - it's easy.
end

2 个评论
显示无隐藏无

Meshooo 2014-11-16

编辑：Meshooo 2014-11-16

Thank you very much Image Analyst. I think it is similar to one old post that you answered some time ago. I tried but didn't work and I wrote a comment in your answer:

http://www.mathworks.com/matlabcentral/answers/152281-calculate-the-distance-between-two-objects-automatically-using-matlab

Is there any easier way to do that?

Thank you.