Image processing of moving marble

Hello. I need to write a code for a project which is about a ball that is passing through a circular shape. Why i need basically is to track the balls and showing the path that they followed and also finding the location where the balls exiting the circular shape. Thanks a lot. Any help will be highly appreciated.

Answer 1

[Image Analyst]

For each snapshot, find the binary image of the ball, by thresholding or color segmentation or optical flow or whatever method you want. Then use bwboundaries() to get the outline of the ball.

binaryImage = bwareafilt(binaryImage, 1); % Take only one blob
boundaries = bwboundaries(binaryImage);
thisBoundary = boundaries{1};
boundaryX = thisBoundary (:,2);
boundaryY = thisBoundary (:,1);
% Put "hold on" and plot the boundaries over the image.  
hold on;
plot(boundaryX, boundaryY, 'r-');

Now you should know the center and radius of your large circle. First of all plot it. Then see if any of the boundary points is farther from the center than your radius.

distances = sqrt((boundaryX - centerX).^2 + (boundaryY - centerY) .^ 2);
if max(distances) > bigCircleRadius
    % Ball has left the circle
else
    % Ball is still completely contained in the big circle.
end

If any distance is greater than the radius, then at least some part of the ball has left the circle. If you need to see how to get the boundary coordinates, see my Image Segmentation Tutorial: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862