curvature versus slope
  n = 657180 
  X=0, Y = 5.96 +/- 3.97 
  Weighted least-squares fit:  Y = 5.0 + 4.594 X  + -0.05078 X**2 

slope versus dZ, curvature < 5
  n = 445738 
  X=0, Y = 6.75 +/- 4.19 
  Weighted least-squares fit:  Y = 6.4 + 0.362 X  + -0.00217 X**2 
     at X = 100, Y = 20.9 
     effective RMSE xy = 31.2 

slope versus dZ, curvature < 15
  n = 586580 
  X=0, Y = 6.74 +/- 4.26 
  Weighted least-squares fit:  Y = 6.8 + 0.369 X  + -0.00021 X**2 

curvature versus dZ, slope < 10
  n = 528365 
  X=0, Y = 7.55 +/- 4.58 
  Weighted least-squares fit:  Y = 7.1 + 1.180 X  + 0.11683 X**2 


Number of samples 659845
Max dz = 700
Mean dz = 9
RMS dz = 19.4935886896
100cm = 99.553076859 percentile value of dz