curvature versus slope
  n = 1104051 
  X=0, Y = 4.81 +/- 2.52 
  Weighted least-squares fit:  Y = 3.7 + 1.863 X  + 0.02839 X**2 

slope versus dZ, curvature < 5
  n = 822811 
  X=0, Y = 8.99 +/- 8.07 
  Weighted least-squares fit:  Y = 7.5 + 0.207 X  + 0.00033 X**2 
     at X = 100, Y = 31.6 
     effective RMSE xy = 48.1 

slope versus dZ, curvature < 15
  n = 1076461 
  X=0, Y = 9.56 +/- 8.24 
  Weighted least-squares fit:  Y = 7.7 + 0.298 X  + -0.00092 X**2 

curvature versus dZ, slope < 10
  n = 1062485 
  X=0, Y = 8.18 +/- 5.87 
  Weighted least-squares fit:  Y = 7.6 + 1.194 X  + 0.10997 X**2 


Number of samples 1104186
Max dz = 300
Mean dz = 7
RMS dz = 9.48683298051
100cm = 99.9880454923 percentile value of dz