Finding center of a line
显示 更早的评论
Hi i need to find the center of a line.A robot needs to foolow this line in real time but my problem is how to find the center of a line.I used bwmorph(image,'thin',inf); and i get the that my thick line thins to a line with 1 pixel size.
so now the only thing that i need is to calculate the distance between the center of my image (blue +) and the line so i could say to my robot move to left so that the center of the line is equal to the image center. .
采纳的回答
Kevin Moerman
2012-2-2
0 个投票
If your edge/line is the only segmented object (only the line consists of ones) in your image then if M is your binary image (containing ones for white) then: [I,J]=find(M); %equivalent to find(M==1) gives you the I and J indices or image coordinates of the whole line. If your line is straight then the mean of these coordinates is the same as the mean of the first and last coordinate and thus gives you the middle.
If you have multiple objects in the image with ones, not just your line. Then you could filter those out based on size/shape criteria and do the above. Alternatively could create an adjacency matrix whereby you check whether pixels are one and also have neighbours in the line direction that are one. For the end points of the line the latter will be false which allows you to find them. But this depends on the quality and thickness of your line depictions. So not sure if this would work. Also you could develop a type of mask (filter) that will highlight the ends of lines. But I would go for the simple mean of the object approach.
Kevin
更多回答（2 个）
Image Analyst
2012-1-30
0 个投票
How about using the Pythagorean Theorem? Look up MATLAB's hypot() function.
3 个评论
samir
2012-1-30
Image Analyst
2012-1-30
You're right, if the "line" is not straight. You can't just find the centroid because the centroid may not line on or in the line. You could try bwboundaries() and play around with what that returns.
samir
2012-1-31
Kevin Moerman
2012-1-31
0 个投票
If its a straight line then you could simply take the mean of your line coordinates (or even centre of gravity of the image object).
If the line is curved then sum up line segments to get total curve length (calculate point-to-point distances and use cumsum for instance), and then solve for (e.g. interpolate) what coordinate describes half of the curve length.
类别
在 帮助中心 和 File Exchange 中查找有关 Image Processing Toolbox 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
