curvature versus slope
  n = 393593 
  X=0, Y = 11.07 +/- 9.70 
  Weighted least-squares fit:  Y = 20.8 + 3.878 X  + -0.04344 X**2 

slope versus dZ, curvature < 5
  n = 189940 
  X=0, Y = 12.52 +/- 8.22 
  Weighted least-squares fit:  Y = 5.9 + 0.488 X  + 0.00171 X**2 
     at X = 100, Y = 71.7 
     effective RMSE xy = 112.3 

slope versus dZ, curvature < 15
  n = 273557 
  X=0, Y = 12.89 +/- 8.37 
  Weighted least-squares fit:  Y = 5.8 + 0.543 X  + 0.00091 X**2 

curvature versus dZ, slope < 10
  n = 193424 
  X=0, Y = 8.87 +/- 6.07 
  Weighted least-squares fit:  Y = 8.2 + 0.976 X  + 0.11878 X**2 


Number of samples 400991
Max dz = 900
Mean dz = 23
RMS dz = 49.1833305094
100cm = 95.5422939667 percentile value of dz