curvature versus slope
  n = 111236 
  X=0, Y = 40.47 +/- 30.77 
  Weighted least-squares fit:  Y = 77.0 + 0.793 X  + -0.00797 X**2 

slope versus dZ, curvature < 5
  n = 3052 

  Weighted least-squares fit:  Y = 45.1 + 0.281 X  + -0.00093 X**2 
     at X = 100, Y = 63.8 
     effective RMSE xy = 71.0 

slope versus dZ, curvature < 15
  n = 8436 

  Weighted least-squares fit:  Y = 43.5 + 0.431 X  + -0.00174 X**2 

curvature versus dZ, slope < 10
  n = 669 
  X=0, Y = 46.47 +/- 8.85 
  Weighted least-squares fit:  Y = 47.8 + -1.862 X  + 0.19647 X**2 


Number of samples 112124
Max dz = 900
Mean dz = 86
RMS dz = 147.587262323
100cm = 71.7518104955 percentile value of dz