curvature versus slope
  n = 1101421 
  X=0, Y = 5.05 +/- 3.66 
  Weighted least-squares fit:  Y = 3.8 + 5.620 X  + -0.07892 X**2 

slope versus dZ, curvature < 5
  n = 834177 
  X=0, Y = 7.32 +/- 6.53 
  Weighted least-squares fit:  Y = 6.8 + 0.349 X  + 0.00020 X**2 
     at X = 100, Y = 43.8 
     effective RMSE xy = 67.9 

slope versus dZ, curvature < 15
  n = 1039588 
  X=0, Y = 7.62 +/- 6.69 
  Weighted least-squares fit:  Y = 6.9 + 0.446 X  + -0.00035 X**2 

curvature versus dZ, slope < 10
  n = 951174 
  X=0, Y = 7.54 +/- 5.63 
  Weighted least-squares fit:  Y = 7.2 + 1.790 X  + 0.07781 X**2 


Number of samples 1102550
Max dz = 900
Mean dz = 8
RMS dz = 13.3041346957
100cm = 99.8858101673 percentile value of dz