how to plot speed graph from centroid of the detected object in image processing ?
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Biswas Lohani V K
on 14 May 2016
Commented: Image Analyst
on 15 May 2016
Dear All,
i would like to plot the speed of the detected object moving only in the x direction in real time.(Not y direction) so i have tried with the following code but didn't get the appropriate solution. please find the attached code and graph i have sending with this file. the graph is not correct because i didnt understant how to implement the following formula
speed= distance/ time,
how can i modified the attached code to display the detected object and speed of moving object from centroid only in the x-direction as in the attached figure in real time.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/164249/image.jpeg)
hope for your appropriate solution.
Thank you.
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Accepted Answer
Image Analyst
on 14 May 2016
Add a third axes control. Then get the object alone by cropping it from the entire image using the object's bounding box and the imcrop() function. Then display the cropped image in the third axes.
4 Comments
Image Analyst
on 15 May 2016
Let's assume 1 object. For each frame you should calculate the centroid location. So now you have x and y vectors. You can also keep distance, speed, and acceleration arrays in your loop over frames.
thisDistance = sqrt((x(frame)-x(frame-1)^2+(y(frame)-y(frame-1))^2);
distance(frame) = distance(frame-1) + thisDistance;
frameTime = toc;
speed(frame) = thisDistance / frameTime; % Frame time is like 1/10 or /130 of a second or whatever. use tic and toc to get exact time.
accel(frame) = (speed(frame) - speed(frame-1)) / frameTime;
and so on.
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