curvature versus slope
  n = 1197393 
  X=0, Y = 40.91 +/- 28.48 
  Weighted least-squares fit:  Y = 70.3 + 1.357 X  + -0.01477 X**2 

slope versus dZ, curvature < 5
  n = 25713 

  Weighted least-squares fit:  Y = 88.7 + 0.399 X  + -0.00076 X**2 
     at X = 100, Y = 120.9 
     effective RMSE xy = 129.2 

slope versus dZ, curvature < 15
  n = 85192 

  Weighted least-squares fit:  Y = 88.7 + 0.390 X  + -0.00066 X**2 

curvature versus dZ, slope < 10
  n = 6197 
  X=0, Y = 94.78 +/- 44.35 
  Weighted least-squares fit:  Y = 86.3 + 2.330 X  + 0.02107 X**2 


Number of samples 1202126
Max dz = 900
Mean dz = 113
RMS dz = 148.684229157
100cm = 51.49343746 percentile value of dz