Create a top road view using warpPerspective () opencv

I am trying to implement Reverse Perspective Mapping to calculate the distance to another vehicle on the road. I know that I need to generate a transformation matrix with starting and ending points before applying the function warpPerspective(), but I don’t know how to calculate the end points.

I searched this forum and other sites, but I can’t convert the first image to the second:

_{(source: shanetuohy.com )}

_{(source: shanetuohy.com )}