How to draw trajectory line from detected object

How can I draw the trajectory line on detected object from video? The object will move from fig1.jpg position to fig2.jpg position. How can I get the red point position and draw the trajectory line? Would you please help, thanks.

Answer 1

[Image Analyst]

I would think that plot should be able to do it:

hold on;
plot([x1,x2], [y1,y2], 'r-', 'LineWidth', 2);

You just need to use the x and y that you used to draw the red spots, which you should already have since I see them in your images.

[Leona Chan]

Thank you for your answer. I want to draw a point in the detected object from the video. And in the last, from those points I can plot a trajectory line. Since these points show in fig1 & fig2 are draw by manually.

1. May I ask how to auto draw the point on each frame?
2. If I got the points, should I store in the array for plot a line finally ?

[Image Analyst]

Not exactly where the red spot should go, but I think you can erode the binary image until the "shaft" is gone and all that's there is the "head" of the golf club. Then get the centroid.

binaryImage = imerode(binaryImage, true(3)); % Get rid of shaft.
binaryImage = bwareafilt(binaryImage, 1); % Take only the largest remaining blob.
props = regionprops(binaryImage, 'Centroid'); % Find centroid of blob.
x = props.Centroid(1);
y = props.Centroid(2);

[Leona Chan]

Done, thank you very much