curvature versus slope
  n = 700031 
  X=0, Y = 64.29 +/- 24.83 
  Weighted least-squares fit:  Y = 70.1 + 1.318 X  + -0.01387 X**2 

slope versus dZ, curvature < 5
  n = 138705 

  Weighted least-squares fit:  Y = 29.8 + 0.520 X  + -0.00073 X**2 
     at X = 100, Y = 74.4 
     effective RMSE xy = 107.2 

slope versus dZ, curvature < 15
  n = 342576 

  Weighted least-squares fit:  Y = 28.6 + 0.728 X  + -0.00194 X**2 

curvature versus dZ, slope < 10
  n = 2238 
  X=0, Y = 29.54 +/- 20.74 
  Weighted least-squares fit:  Y = 31.9 + 1.134 X  + -0.04635 X**2 


Number of samples 710903
Max dz = 900
Mean dz = 67
RMS dz = 91.0549284773
100cm = 77.5212652078 percentile value of dz