curvature versus slope
  n = 952681 
  X=0, Y = 54.50 +/- 29.46 
  Weighted least-squares fit:  Y = 64.8 + 1.161 X  + -0.01039 X**2 

slope versus dZ, curvature < 5
  n = 47966 

  Weighted least-squares fit:  Y = 10.4 + 0.426 X  + -0.00020 X**2 
     at X = 100, Y = 51.0 
     effective RMSE xy = 78.4 

slope versus dZ, curvature < 15
  n = 183852 

  Weighted least-squares fit:  Y = 13.2 + 0.395 X  + 0.00024 X**2 

curvature versus dZ, slope < 10
  n = 3195 
  X=0, Y = 11.33 +/- 7.85 
  Weighted least-squares fit:  Y = 9.5 + 3.592 X  + -0.01938 X**2 


Number of samples 959769
Max dz = 900
Mean dz = 51
RMS dz = 75.3591401225
100cm = 86.2008462453 percentile value of dz