curvature versus slope
  n = 273983 
  X=0, Y = 68.20 +/- 26.10 
  Weighted least-squares fit:  Y = 78.9 + 0.704 X  + -0.00701 X**2 

slope versus dZ, curvature < 5
  n = 8999 

  Weighted least-squares fit:  Y = 17.1 + -0.033 X  + 0.00539 X**2 
     at X = 100, Y = 67.7 
     effective RMSE xy = 102.8 

slope versus dZ, curvature < 15
  n = 29856 

  Weighted least-squares fit:  Y = 17.7 + 0.109 X  + 0.00414 X**2 

curvature versus dZ, slope < 10
  n = 375 
  X=0, Y = 13.98 +/- 5.57 
  Weighted least-squares fit:  Y = 15.0 + 0.641 X  + 0.05720 X**2 


Number of samples 276893
Max dz = 900
Mean dz = 82
RMS dz = 113.85956262
100cm = 69.248771186 percentile value of dz