curvature versus slope
  n = 1476135 
  X=0, Y = 32.36 +/- 24.09 
  Weighted least-squares fit:  Y = 32.0 + 1.419 X  + -0.01089 X**2 

slope versus dZ, curvature < 5
  n = 9708 

  Weighted least-squares fit:  Y = 3.2 + 0.117 X  + 0.00075 X**2 
     at X = 100, Y = 22.4 
     effective RMSE xy = 34.8 

slope versus dZ, curvature < 15
  n = 45730 

  Weighted least-squares fit:  Y = 3.5 + 0.087 X  + 0.00145 X**2 

curvature versus dZ, slope < 10
  n = 98688 
  X=0, Y = 4.16 +/- 2.18 
  Weighted least-squares fit:  Y = 4.0 + 0.129 X  + 0.00133 X**2 


Number of samples 1479752
Max dz = 900
Mean dz = 16
RMS dz = 24.7790233867
100cm = 99.6950840411 percentile value of dz
Mean dz (curv<=5) = 5
RMS dz (curv<=5) = 8.94427191