curvature versus slope
  n = 745500 
  X=0, Y = 6.70 +/- 4.78 
  Weighted least-squares fit:  Y = 6.8 + 4.602 X  + -0.04567 X**2 

slope versus dZ, curvature < 5
  n = 450165 
  X=0, Y = 8.06 +/- 4.70 
  Weighted least-squares fit:  Y = 7.8 + 0.490 X  + -0.00071 X**2 
     at X = 100, Y = 49.6 
     effective RMSE xy = 77.0 

slope versus dZ, curvature < 15
  n = 643892 
  X=0, Y = 8.46 +/- 5.04 
  Weighted least-squares fit:  Y = 8.5 + 0.516 X  + -0.00119 X**2 

curvature versus dZ, slope < 10
  n = 531807 
  X=0, Y = 8.89 +/- 5.81 
  Weighted least-squares fit:  Y = 8.6 + 2.176 X  + 0.05959 X**2 


Number of samples 750573
Max dz = 900
Mean dz = 12
RMS dz = 24.4948974278
100cm = 99.2544362774 percentile value of dz