curvature versus slope
  n = 554602 
  X=0, Y = 9.85 +/- 8.22 
  Weighted least-squares fit:  Y = 15.0 + 3.981 X  + -0.04542 X**2 

slope versus dZ, curvature < 5
  n = 282023 
  X=0, Y = 8.20 +/- 5.14 
  Weighted least-squares fit:  Y = 8.0 + 0.235 X  + 0.00137 X**2 
     at X = 100, Y = 45.3 
     effective RMSE xy = 70.0 

slope versus dZ, curvature < 15
  n = 402859 
  X=0, Y = 8.99 +/- 5.64 
  Weighted least-squares fit:  Y = 8.2 + 0.298 X  + 0.00097 X**2 

curvature versus dZ, slope < 10
  n = 304764 
  X=0, Y = 8.79 +/- 5.80 
  Weighted least-squares fit:  Y = 7.9 + 1.813 X  + 0.01847 X**2 


Number of samples 565853
Max dz = 900
Mean dz = 17
RMS dz = 34.8425027804
100cm = 97.7317430499 percentile value of dz