curvature versus slope
  n = 381356 
  X=0, Y = 7.49 +/- 5.14 
  Weighted least-squares fit:  Y = 7.6 + 4.691 X  + -0.05220 X**2 

slope versus dZ, curvature < 5
  n = 285482 
  X=0, Y = 13.44 +/- 6.96 
  Weighted least-squares fit:  Y = 9.7 + 0.560 X  + -0.00403 X**2 
     at X = 100, Y = 25.3 
     effective RMSE xy = 36.8 

slope versus dZ, curvature < 15
  n = 348463 
  X=0, Y = 13.42 +/- 7.01 
  Weighted least-squares fit:  Y = 10.4 + 0.459 X  + -0.00139 X**2 

curvature versus dZ, slope < 10
  n = 301346 
  X=0, Y = 12.26 +/- 7.19 
  Weighted least-squares fit:  Y = 12.0 + 0.360 X  + 0.17212 X**2 


Number of samples 384399
Max dz = 900
Mean dz = 14
RMS dz = 27.2396769438
100cm = 99.1318916022 percentile value of dz