curvature versus slope
  n = 222760 
  X=0, Y = 16.67 +/- 13.22 
  Weighted least-squares fit:  Y = 24.1 + 3.976 X  + -0.04639 X**2 

slope versus dZ, curvature < 5
  n = 110689 
  X=0, Y = 9.39 +/- 4.70 
  Weighted least-squares fit:  Y = 8.2 + 0.441 X  + -0.00123 X**2 
     at X = 100, Y = 40.1 
     effective RMSE xy = 61.6 

slope versus dZ, curvature < 15
  n = 150677 
  X=0, Y = 9.26 +/- 4.60 
  Weighted least-squares fit:  Y = 8.6 + 0.401 X  + -0.00024 X**2 

curvature versus dZ, slope < 10
  n = 84210 
  X=0, Y = 10.82 +/- 6.26 
  Weighted least-squares fit:  Y = 10.4 + 0.881 X  + 0.05791 X**2 


Number of samples 224296
Max dz = 900
Mean dz = 19
RMS dz = 47.4236228055
100cm = 98.1216784963 percentile value of dz