Bah. Absolutely, a lot of Poser renders look less than realistic. But...there are paintings that do seem "alive." Or at least that have a closer seeming to real people. So it isn't something inherent to the act of transferring a human to an image of a human -- hey, even a photo is just pixels when you get it on to a computer monitor -- but some lack of how Poser is applied to the task. My take comes sideways from Mori ("The Uncanny Valley.") Painting works by being impressionistic; fudging details but presenting the sense of reality to the viewer. Poser is generally asked to provide a very detailed, very realistic look, and this bares to the eye a multitude of subtle flaws. An almost-perfect duplicate of a face is a lot easier for our brains to critique than a sketch or impressionist daub of the same face. To my eye, the greatest failure in most Poser renders is in the pose. The curves and flows and stresses and balances of the human body are hard to capture with the dial interface and within the limitations of the rigging.