curvature versus slope
  n = 245375 
  X=0, Y = 13.61 +/- 8.46 
  Weighted least-squares fit:  Y = 18.9 + 4.045 X  + -0.04529 X**2 

slope versus dZ, curvature < 5
  n = 140623 
  X=0, Y = 5.39 +/- 4.59 
  Weighted least-squares fit:  Y = 10.6 + 0.130 X  + 0.00103 X**2 
     at X = 100, Y = 33.9 
     effective RMSE xy = 50.7 

slope versus dZ, curvature < 15
  n = 178094 
  X=0, Y = 8.88 +/- 7.38 
  Weighted least-squares fit:  Y = 10.5 + 0.163 X  + 0.00181 X**2 

curvature versus dZ, slope < 10
  n = 98488 
  X=0, Y = 12.28 +/- 7.48 
  Weighted least-squares fit:  Y = 11.4 + 0.989 X  + 0.03985 X**2 


Number of samples 247884
Max dz = 900
Mean dz = 22
RMS dz = 61.3921819127
100cm = 96.2046763809 percentile value of dz