curvature versus slope
  n = 422061 
  X=0, Y = 11.69 +/- 10.54 
  Weighted least-squares fit:  Y = 15.7 + 4.917 X  + -0.06095 X**2 

slope versus dZ, curvature < 5
  n = 222480 
  X=0, Y = 10.29 +/- 7.84 
  Weighted least-squares fit:  Y = 10.2 + 0.511 X  + 0.00072 X**2 
     at X = 100, Y = 68.5 
     effective RMSE xy = 106.4 

slope versus dZ, curvature < 15
  n = 335305 
  X=0, Y = 10.89 +/- 8.14 
  Weighted least-squares fit:  Y = 10.5 + 0.540 X  + 0.00040 X**2 

curvature versus dZ, slope < 10
  n = 233016 
  X=0, Y = 12.54 +/- 7.74 
  Weighted least-squares fit:  Y = 12.1 + 1.417 X  + 0.08133 X**2 


Number of samples 431588
Max dz = 900
Mean dz = 21
RMS dz = 39.1152144312
100cm = 97.199644105 percentile value of dz