curvature versus slope
  n = 88259 
  X=0, Y = 50.53 +/- 36.91 
  Weighted least-squares fit:  Y = 75.7 + 1.060 X  + -0.01020 X**2 

slope versus dZ, curvature < 5
  n = 2601 

  Weighted least-squares fit:  Y = 35.9 + 0.118 X  + 0.00237 X**2 
     at X = 100, Y = 71.4 
     effective RMSE xy = 96.9 

slope versus dZ, curvature < 15
  n = 8827 

  Weighted least-squares fit:  Y = 34.0 + 0.264 X  + 0.00186 X**2 

curvature versus dZ, slope < 10
  n = 723 
  X=0, Y = 37.58 +/- 15.52 
  Weighted least-squares fit:  Y = 38.0 + -1.431 X  + 0.13905 X**2 


Number of samples 89053
Max dz = 900
Mean dz = 89
RMS dz = 144.076368638
100cm = 69.5114145509 percentile value of dz