curvature versus slope
  n = 451715 
  X=0, Y = 12.47 +/- 8.31 
  Weighted least-squares fit:  Y = 18.4 + 3.753 X  + -0.04161 X**2 

slope versus dZ, curvature < 5
  n = 193623 
  X=0, Y = 10.15 +/- 6.21 
  Weighted least-squares fit:  Y = 7.7 + 0.267 X  + 0.00043 X**2 
     at X = 100, Y = 38.7 
     effective RMSE xy = 59.6 

slope versus dZ, curvature < 15
  n = 278423 
  X=0, Y = 10.12 +/- 6.12 
  Weighted least-squares fit:  Y = 7.2 + 0.353 X  + -0.00004 X**2 

curvature versus dZ, slope < 10
  n = 158771 
  X=0, Y = 9.45 +/- 5.69 
  Weighted least-squares fit:  Y = 7.3 + 2.118 X  + 0.01445 X**2 


Number of samples 456464
Max dz = 900
Mean dz = 22
RMS dz = 48.4045452411
100cm = 96.6242682884 percentile value of dz