ABSTRACT
The techniques for producing these images aren't complicated, but require a bit more thought than a simple rendering or screen capture.
For a model with a shadow beneath it, place a plane at the floor level (usually just touching the bottom of the model) and point a shadow-casting light at the model. Then create a Matte/Shadow material and apply it to the object. When you render, only the shadow cast by the object will appear on the plane, and the rest of the plane will be invisible.
