curvature versus slope
  n = 1064925 
  X=0, Y = 8.98 +/- 6.40 
  Weighted least-squares fit:  Y = 12.4 + 4.489 X  + -0.04959 X**2 

slope versus dZ, curvature < 5
  n = 416274 
  X=0, Y = 8.63 +/- 5.18 
  Weighted least-squares fit:  Y = 8.9 + 0.210 X  + 0.00150 X**2 
     at X = 100, Y = 44.9 
     effective RMSE xy = 69.1 

slope versus dZ, curvature < 15
  n = 715820 
  X=0, Y = 8.97 +/- 5.34 
  Weighted least-squares fit:  Y = 9.4 + 0.267 X  + 0.00111 X**2 

curvature versus dZ, slope < 10
  n = 561571 
  X=0, Y = 9.45 +/- 5.60 
  Weighted least-squares fit:  Y = 8.9 + 1.769 X  + 0.00626 X**2 


Number of samples 1081842
Max dz = 900
Mean dz = 22
RMS dz = 50.2692749102
100cm = 95.9944243244 percentile value of dz