curvature versus slope
  n = 874579 
  X=0, Y = 33.69 +/- 21.52 
  Weighted least-squares fit:  Y = 45.5 + 2.045 X  + -0.02120 X**2 

slope versus dZ, curvature < 5
  n = 118638 

  Weighted least-squares fit:  Y = 11.1 + 0.205 X  + 0.00186 X**2 
     at X = 100, Y = 50.1 
     effective RMSE xy = 76.8 

slope versus dZ, curvature < 15
  n = 320413 

  Weighted least-squares fit:  Y = 11.9 + 0.235 X  + 0.00172 X**2 

curvature versus dZ, slope < 10
  n = 33333 
  X=0, Y = 12.36 +/- 7.85 
  Weighted least-squares fit:  Y = 10.7 + 1.852 X  + 0.03618 X**2 


Number of samples 885856
Max dz = 900
Mean dz = 35
RMS dz = 60.1498129673
100cm = 92.2911850233 percentile value of dz