The smoothness parameter influences the surface reconstruction and fades between smooth surfaces (closer to 1) and more crisp reconstructions (closer to 0). The special value of 0 will use a pretrained value for your current FlexView image count.
Lower values give more weight to the local cost function (e.g. window comparison), higher values will allow more influence from extrapolations of neighboring pixels.
A number in [0..1] fading between smooth and crisp reconstruction.
Depending on the Automatic parameter.