curvature versus slope
  n = 282550 
  X=0, Y = 45.71 +/- 35.03 
  Weighted least-squares fit:  Y = 73.8 + 1.186 X  + -0.01212 X**2 

slope versus dZ, curvature < 5
  n = 4197 

  Weighted least-squares fit:  Y = 10.0 + 0.441 X  + 0.00198 X**2 
     at X = 100, Y = 74.0 
     effective RMSE xy = 115.1 

slope versus dZ, curvature < 15
  n = 17693 

  Weighted least-squares fit:  Y = 10.1 + 0.579 X  + 0.00133 X**2 

curvature versus dZ, slope < 10
  n = 1643 
  X=0, Y = 11.90 +/- 6.81 
  Weighted least-squares fit:  Y = 11.7 + 2.199 X  + -0.11596 X**2 


Number of samples 284669
Max dz = 900
Mean dz = 95
RMS dz = 136.773535452
100cm = 64.8107099825 percentile value of dz