How to remove perspective from images?

Hello everybody,

I'm trying to remove perspective from images in order to evaluate velocities of moving objects during a video. In particular, I have a traffic camera at one edge of a highway and I want to assess drivers velocity. As you may imagine, it's impossible to do that without removing perspective before, due to different distances travelled in every frame. (Near the camera vehicles "run more pixels", than at the end).

I calibrated the camera, so I have all cameraParameters both intrinsics and extrinsics. I have already removed lens distortion using 'undistortImage' function, so I'm wondering whether there's something similar to remove perspective so then I may have a view of the street level to evaluate velocities and trajectories properly. Here, what I made for lenses distortion:

Could you help me to remove perspective distortion too, please?