curvature versus slope
  n = 118017 
  X=0, Y = 20.25 +/- 15.67 
  Weighted least-squares fit:  Y = 32.0 + 3.278 X  + -0.03568 X**2 

slope versus dZ, curvature < 5
  n = 33881 

  Weighted least-squares fit:  Y = 5.7 + 0.194 X  + 0.00048 X**2 
     at X = 100, Y = 29.9 
     effective RMSE xy = 46.1 

slope versus dZ, curvature < 15
  n = 60017 
  X=0, Y = 4.53 +/- 0.71 
  Weighted least-squares fit:  Y = 7.1 + 0.112 X  + 0.00271 X**2 

curvature versus dZ, slope < 10
  n = 24293 
  X=0, Y = 7.28 +/- 4.22 
  Weighted least-squares fit:  Y = 6.4 + 1.623 X  + 0.00030 X**2 


Number of samples 118741
Max dz = 900
Mean dz = 28
RMS dz = 81.4186710773
100cm = 94.0652344178 percentile value of dz