curvature versus slope
  n = 324674 
  X=0, Y = 58.85 +/- 16.13 
  Weighted least-squares fit:  Y = 63.7 + 1.818 X  + -0.02302 X**2 

slope versus dZ, curvature < 5
  n = 200564 

  Weighted least-squares fit:  Y = -1.0 + 1.229 X  + -0.00546 X**2 
     at X = 100, Y = 67.3 
     effective RMSE xy = 105.7 

slope versus dZ, curvature < 15
  n = 282926 

  Weighted least-squares fit:  Y = -1.1 + 1.264 X  + -0.00539 X**2 

curvature versus dZ, slope < 10
  n = 39 
  X=0, Y = 12.23 +/- 3.42 
  Weighted least-squares fit:  Y = 12.2 + 7.383 X  + -3.81763 X**2 


Number of samples 331355
Max dz = 900
Mean dz = 60
RMS dz = 90.642153549
100cm = 91.7620075146 percentile value of dz