3D model from high speed videos?
You'd basically need to do two things:


find a 3D-model of your environment, and track the ball in that. This model needs to have knowledge of the materials involved. Since a video gives you no information on the involved object's radar reflectivity, scattering coefficients and other RF parameters, that's something that you'll have to enhance your model with – manually. 
Simulate the environment (e.g. via ray-tracing/volumetric RF FEM) as RF environment, and in that simulation emit your radar signal and observe the echo.


Honestly, I don't think this is overly viable ask "task I have", unless "I" is very much more experienced in RF simulations than I am, or "I" is a medium to large team of researchers.