Quote - When using shadow maps of any resoution (especially small), remember that Poser calculates the map based on the total area of shadow casting objects.  So if you have two figures standing on the "ground", your render will look better if you turn shadows off for the "ground".

I could have written this better.  What I meant to say is do not have your ground object cast a shadow.  If your two figures are in the middle of the ground your shadow map will only be calculated for the bounding box around them, so even a low res shadowmap will look OK.  However, if you turn the shadow casting on for the ground, then the bounding box has to include the figures and the ground.  So, even a high res shadow map would then look blocky.

I should point out that, in a case where you had for example a figure walking away from another, that your shadow map's bounding box will change as the figures become farther apart.  This will cause the shadow to become less sharp as the distance increases, and may cause a shimmering effect in your renders.  Still, I recommend a low res shadow map over no map in most cases.