curvature versus slope
  n = 422659 
  X=0, Y = 30.42 +/- 26.28 
  Weighted least-squares fit:  Y = 68.9 + 1.328 X  + -0.01360 X**2 

slope versus dZ, curvature < 5
  n = 10920 

  Weighted least-squares fit:  Y = 18.6 + 0.352 X  + 0.00215 X**2 
     at X = 100, Y = 75.3 
     effective RMSE xy = 114.6 

slope versus dZ, curvature < 15
  n = 33788 

  Weighted least-squares fit:  Y = 18.4 + 0.534 X  + 0.00050 X**2 

curvature versus dZ, slope < 10
  n = 6280 
  X=0, Y = 19.93 +/- 9.22 
  Weighted least-squares fit:  Y = 22.4 + 0.642 X  + 0.04301 X**2 


Number of samples 425552
Max dz = 900
Mean dz = 75
RMS dz = 104.79503805
100cm = 73.2881058014 percentile value of dz