You might also want to be aware that even with smoothing enabled, the cast shadow remains that of the unsmoothed object (i.e. faceted - you see it clearly if the object is low poly with smoothing enabled and no shadow blur is used on a RT light). This possibly also adds to potential artifacts related to ray bias.

Something I'm unsure of is whether there is a bias at work with IDL as with AO (I'd assume there is but perhaps not). If so, it'd be useful to have some control over this.
And on the question of raising shadow bias when smoothing is used and how it might affect different objects/figures in a scene, perhaps it might be useful to have control over bias on a per object level as well as per light. I'm not entirely sure whether this even makes sense, let alone if it's possible, but there have certainly been times for me when it seems as if it would be.

 

PoserPro2014(Sr4), Win7 x64, display units set to inches.

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