curvature versus slope
  n = 303145 
  X=0, Y = 40.70 +/- 28.91 
  Weighted least-squares fit:  Y = 64.1 + 1.521 X  + -0.01592 X**2 

slope versus dZ, curvature < 5
  n = 13871 

  Weighted least-squares fit:  Y = 3.8 + 0.784 X  + -0.00106 X**2 
     at X = 100, Y = 71.7 
     effective RMSE xy = 112.4 

slope versus dZ, curvature < 15
  n = 44265 

  Weighted least-squares fit:  Y = 5.2 + 0.821 X  + -0.00117 X**2 

curvature versus dZ, slope < 10
  n = 2491 
  X=0, Y = 8.07 +/- 5.15 
  Weighted least-squares fit:  Y = 8.1 + 2.545 X  + 0.00010 X**2 


Number of samples 305913
Max dz = 900
Mean dz = 69
RMS dz = 104.225716596
100cm = 77.0614521122 percentile value of dz