curvature versus slope
  n = 79371 
  X=0, Y = 44.18 +/- 36.49 
  Weighted least-squares fit:  Y = 77.7 + 0.983 X  + -0.01027 X**2 

slope versus dZ, curvature < 5
  n = 6338 

  Weighted least-squares fit:  Y = 4.6 + 1.018 X  + -0.00226 X**2 
     at X = 100, Y = 83.9 
     effective RMSE xy = 131.5 

slope versus dZ, curvature < 15
  n = 17555 

  Weighted least-squares fit:  Y = 5.4 + 1.013 X  + -0.00105 X**2 

curvature versus dZ, slope < 10
  n = 1500 
  X=0, Y = 10.12 +/- 5.47 
  Weighted least-squares fit:  Y = 9.8 + 3.340 X  + -0.05481 X**2 


Number of samples 80218
Max dz = 900
Mean dz = 87
RMS dz = 148.468851952
100cm = 69.4931312174 percentile value of dz