curvature versus slope
  n = 424296 
  X=0, Y = 13.75 +/- 12.14 
  Weighted least-squares fit:  Y = 20.1 + 3.996 X  + -0.04445 X**2 

slope versus dZ, curvature < 5
  n = 197780 
  X=0, Y = 5.14 +/- 4.88 
  Weighted least-squares fit:  Y = 8.5 + 0.292 X  + 0.00255 X**2 
     at X = 100, Y = 63.2 
     effective RMSE xy = 98.4 

slope versus dZ, curvature < 15
  n = 311013 
  X=0, Y = 5.65 +/- 5.32 
  Weighted least-squares fit:  Y = 9.2 + 0.387 X  + 0.00153 X**2 

curvature versus dZ, slope < 10
  n = 205747 
  X=0, Y = 8.88 +/- 7.07 
  Weighted least-squares fit:  Y = 8.2 + 3.486 X  + -0.12743 X**2 


Number of samples 426570
Max dz = 900
Mean dz = 22
RMS dz = 67.926430791
100cm = 96.480061889 percentile value of dz