curvature versus slope
  n = 231332 
  X=0, Y = 16.86 +/- 13.63 
  Weighted least-squares fit:  Y = 37.1 + 3.134 X  + -0.03551 X**2 

slope versus dZ, curvature < 5
  n = 58418 
  X=0, Y = 7.43 +/- 5.83 
  Weighted least-squares fit:  Y = 4.5 + 0.473 X  + 0.00131 X**2 
     at X = 100, Y = 64.9 
     effective RMSE xy = 101.7 

slope versus dZ, curvature < 15
  n = 94111 
  X=0, Y = 7.43 +/- 5.83 
  Weighted least-squares fit:  Y = 4.3 + 0.582 X  + 0.00073 X**2 

curvature versus dZ, slope < 10
  n = 43876 
  X=0, Y = 7.11 +/- 4.80 
  Weighted least-squares fit:  Y = 6.0 + 2.264 X  + 0.06195 X**2 


Number of samples 235168
Max dz = 900
Mean dz = 45
RMS dz = 82.8552955459
100cm = 86.6210538849 percentile value of dz