I created an animation that looks great except the shadows hardly show on the prop ground I am using.  I want to make an extra pass at the animation but just render the SHADOWS ONLY on the groung using Current BG Shader in the render settings so I can overlay this onto the anmimation.

In order to do this I need to create stronger lighting. I do not want to render figures or anything else - I need these invisible but to get the shadows I need the figure ON.  Is there a setting or way to have the figures cast shadows only?

Windows 10 - Poser Pro 2012 - 64Bit - 24GB RAM - 4 x 3.40 GHZ processor