curvature versus slope
  n = 344493 
  X=0, Y = 51.37 +/- 18.36 
  Weighted least-squares fit:  Y = 54.3 + 1.645 X  + -0.01724 X**2 

slope versus dZ, curvature < 5
  n = 71732 

  Weighted least-squares fit:  Y = 9.1 + 0.110 X  + 0.00117 X**2 
     at X = 100, Y = 31.7 
     effective RMSE xy = 47.7 

slope versus dZ, curvature < 15
  n = 188450 

  Weighted least-squares fit:  Y = 10.1 + 0.097 X  + 0.00124 X**2 

curvature versus dZ, slope < 10
  n = 1106 
  X=0, Y = 8.51 +/- 4.10 
  Weighted least-squares fit:  Y = 7.8 + 2.076 X  + -0.03539 X**2 


Number of samples 347250
Max dz = 600
Mean dz = 20
RMS dz = 28.7576076891
100cm = 99.0888408927 percentile value of dz