curvature versus slope
  n = 926603 
  X=0, Y = 8.32 +/- 6.31 
  Weighted least-squares fit:  Y = 6.9 + 4.576 X  + -0.04987 X**2 

slope versus dZ, curvature < 5
  n = 414991 
  X=0, Y = 8.63 +/- 5.21 
  Weighted least-squares fit:  Y = 7.4 + 0.398 X  + 0.00068 X**2 
     at X = 100, Y = 54.0 
     effective RMSE xy = 84.1 

slope versus dZ, curvature < 15
  n = 729053 
  X=0, Y = 9.01 +/- 5.38 
  Weighted least-squares fit:  Y = 8.7 + 0.420 X  + 0.00042 X**2 

curvature versus dZ, slope < 10
  n = 533356 
  X=0, Y = 8.46 +/- 5.32 
  Weighted least-squares fit:  Y = 8.4 + 2.190 X  + 0.03821 X**2 


Number of samples 934420
Max dz = 900
Mean dz = 13
RMS dz = 25.1594912508
100cm = 99.0878833929 percentile value of dz