Expanding object: how do I calculate the speed of expansion from the movement of the edges?
2 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
Hello everyone,
I have a 320x320X360 cell in which a video of a (more or less) rectangular object is saved. The size of the object increses over the 360 frames and I would like to claculate the speed of expansion of the object and its change over time.
To do that, I would like to track the position of the edges at a certain row and column.
The images in the cell are binarized and I used the Canny method to extract the edges. Also, I know how big a pixel is (80x80 µm)
Until now I only have
for k = 1:framenumber
vertical(:,k) = bin_edge{1,k}(:,160);
horizontal (:,k) = bin_edge{1,k) (160,:);
end
which returns two matrices with zeros and ones, the ones indicating the found edges.
But how do I now calculate the speed from that? How can I measure the "distances", or the number of zeros between the ones (for they represent the edges)?
And what makes it even harder (at least for me, as a beginner) is that in some columns I have more than 2 ones. Sometimes, "edge" finds more edges within the objects, which I would like to exclude for the calculations.
I realy hope you can help me, since I tried for quite some time now and don't have any ideas anymore.
Many thanks from Germany Julian
Respuesta aceptada
Image Analyst
el 5 de Mzo. de 2013
Why are you tracking edges? Why not find the area and log how that changes over the frames?
5 comentarios
Image Analyst
el 6 de Mzo. de 2013
Something like
for col = 1 : columns
thisColumn = yourImage(:, col);
topRow = find(thisColumn, 1, 'first');
bottomRow = find(thisColumn, 1, 'last');
height(col) = bottomRow - topRow; % Add 1 if you're doing pixel based instead of pixel center - to - pixel center.
end
Más respuestas (1)
Julian
el 6 de Mzo. de 2013
Editada: Julian
el 6 de Mzo. de 2013
3 comentarios
Image Analyst
el 6 de Mzo. de 2013
Did you notice the comment I posted above, under my answer, that had some code in it?
Ver también
Categorías
Más información sobre Graphics Object Programming en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!