# How to calculate vehicle speed ?

1. May 31, 2014

### ramdas

hello everyone ,i am doing my project in image processing.i am taking video of car moving on the road and taking video frames of the same.

i want to calculate speed of vehicle.using frame rate i can calculate the time elapsed by vehicle to cover some distance. but i have one difficulty, As the vehicle goes away its size goes down also we can’t use linear scale to compute the distance .for this can anybody help me for distance computation?
or is there any other way to calculate speed vehicle using image processing?
i am doing my coding using matlab software.
i am adding images ,so that u can get an idea about it..thank u

2. May 31, 2014

### Simon Bridge

If you know the dimensions of the vehicle, then you can use the apparent size on the screen to tell you it's distance from the camera in each frame.

If you have a parallel distance scale in the shot (say a row of fence posts with a known separation) you can use that to help you work out the distance covered.

3. May 31, 2014

### ramdas

but sir,nonlinear scale is the biggest problem here.

but sir,nonlinear scale is the biggest problem here...

4. May 31, 2014

### Simon Bridge

Why is that a problem ... if you know the dimensions and geometry of, at least, some of the objects in the frame?

Presumably you also know the properties of the camera - i.e. does the camera move about, or is it stationary?
What sort of lens is used? How high is the camera POV?

Is there something regularly spaced in the frame?

You have to use data from outside the picture to be able to analyse the picture.