curvature versus slope
  n = 123724 
  X=0, Y = 32.13 +/- 26.11 
  Weighted least-squares fit:  Y = 63.4 + 1.697 X  + -0.01790 X**2 

slope versus dZ, curvature < 5
  n = 10065 

  Weighted least-squares fit:  Y = 12.5 + 0.406 X  + 0.00199 X**2 
     at X = 100, Y = 73.0 
     effective RMSE xy = 112.9 

slope versus dZ, curvature < 15
  n = 22629 

  Weighted least-squares fit:  Y = 11.3 + 0.564 X  + 0.00122 X**2 

curvature versus dZ, slope < 10
  n = 4323 
  X=0, Y = 15.76 +/- 13.25 
  Weighted least-squares fit:  Y = 15.4 + 1.127 X  + 0.14235 X**2 


Number of samples 124764
Max dz = 900
Mean dz = 87
RMS dz = 201.002487547
100cm = 75.1915616684 percentile value of dz