curvature versus slope
  n = 75455 
  X=0, Y = 28.93 +/- 23.06 
  Weighted least-squares fit:  Y = 49.9 + 2.304 X  + -0.02403 X**2 

slope versus dZ, curvature < 5
  n = 6667 

  Weighted least-squares fit:  Y = 86.9 + 0.679 X  + -0.00185 X**2 
     at X = 100, Y = 136.4 
     effective RMSE xy = 165.1 

slope versus dZ, curvature < 15
  n = 17224 

  Weighted least-squares fit:  Y = 87.6 + 0.503 X  + 0.00030 X**2 

curvature versus dZ, slope < 10
  n = 4135 
  X=0, Y = 97.20 +/- 32.43 
  Weighted least-squares fit:  Y = 95.2 + -2.073 X  + 0.22233 X**2 


Number of samples 76146
Max dz = 900
Mean dz = 116
RMS dz = 165.571736719
100cm = 48.8732172406 percentile value of dz