code: def _linear_inverse_kamb(cos_dist, sigma=3):
      
      n = float(cos_dist.size)
      radius = _kamb_radius(n, sigma)
      f = 2 / (1 - radius)
      cos_dist = cos_dist[cos_dist >= radius]
      count = (f * (cos_dist - radius))
      return count, _kamb_units(n, radius)
docs: Kernel function from Vollmer for linear smoothing.