curvature versus slope
  n = 62427 
  X=0, Y = 72.38 +/- 23.36 
  Weighted least-squares fit:  Y = 80.0 + 0.946 X  + -0.00986 X**2 

slope versus dZ, curvature < 5
  n = 6409 

  Weighted least-squares fit:  Y = 2.9 + 0.881 X  + 0.00081 X**2 
     at X = 100, Y = 99.1 
     effective RMSE xy = 155.6 

slope versus dZ, curvature < 15
  n = 17157 

  Weighted least-squares fit:  Y = 2.5 + 1.027 X  + -0.00008 X**2 

curvature versus dZ, slope < 10
  n = 39 
  X=0, Y = 6.44 +/- 3.82 
  Weighted least-squares fit:  Y = 6.4 + 4.191 X  + -2.14160 X**2 


Number of samples 63226
Max dz = 900
Mean dz = 93
RMS dz = 140.591607146
100cm = 65.6897478885 percentile value of dz
Mean dz (curv<=5) = 52
RMS dz (curv<=5) = 72.0555341386