curvature versus slope
  n = 770572 
  X=0, Y = 6.76 +/- 4.05 
  Weighted least-squares fit:  Y = 4.0 + 3.129 X  + -0.01169 X**2 

slope versus dZ, curvature < 5
  n = 484782 
  X=0, Y = 15.36 +/- 8.77 
  Weighted least-squares fit:  Y = 15.1 + 0.006 X  + 0.00179 X**2 
     at X = 100, Y = 33.6 
     effective RMSE xy = 47.1 

slope versus dZ, curvature < 15
  n = 723443 
  X=0, Y = 15.62 +/- 9.22 
  Weighted least-squares fit:  Y = 14.6 + 0.131 X  + 0.00198 X**2 

curvature versus dZ, slope < 10
  n = 623853 
  X=0, Y = 15.57 +/- 9.25 
  Weighted least-squares fit:  Y = 14.8 + 0.875 X  + 0.05693 X**2 


Number of samples 770812
Max dz = 600
Mean dz = 13
RMS dz = 16.5831239518
100cm = 99.9656206702 percentile value of dz