curvature versus slope
  n = 820737 
  X=0, Y = 9.77 +/- 8.00 
  Weighted least-squares fit:  Y = 8.1 + 4.106 X  + -0.04041 X**2 

slope versus dZ, curvature < 5
  n = 432341 
  X=0, Y = 8.98 +/- 6.57 
  Weighted least-squares fit:  Y = 9.9 + 0.140 X  + 0.00148 X**2 
     at X = 100, Y = 38.7 
     effective RMSE xy = 58.8 

slope versus dZ, curvature < 15
  n = 701906 
  X=0, Y = 9.19 +/- 6.61 
  Weighted least-squares fit:  Y = 10.5 + 0.212 X  + 0.00111 X**2 

curvature versus dZ, slope < 10
  n = 535393 
  X=0, Y = 10.01 +/- 6.45 
  Weighted least-squares fit:  Y = 9.6 + 1.728 X  + 0.05044 X**2 


Number of samples 822812
Max dz = 800
Mean dz = 12
RMS dz = 21.1423745119
100cm = 99.722415327 percentile value of dz