curvature versus slope
  n = 607453 
  X=0, Y = 11.58 +/- 8.70 
  Weighted least-squares fit:  Y = 19.3 + 4.073 X  + -0.04646 X**2 

slope versus dZ, curvature < 5
  n = 229526 
  X=0, Y = 11.55 +/- 8.53 
  Weighted least-squares fit:  Y = 9.5 + 0.523 X  + -0.00062 X**2 
     at X = 100, Y = 55.5 
     effective RMSE xy = 85.9 

slope versus dZ, curvature < 15
  n = 378867 
  X=0, Y = 11.56 +/- 8.09 
  Weighted least-squares fit:  Y = 10.2 + 0.508 X  + -0.00049 X**2 

curvature versus dZ, slope < 10
  n = 222706 
  X=0, Y = 11.95 +/- 7.57 
  Weighted least-squares fit:  Y = 11.1 + 1.859 X  + 0.03452 X**2 


Number of samples 619234
Max dz = 900
Mean dz = 27
RMS dz = 52.9528091795
100cm = 95.0133552098 percentile value of dz