curvature versus slope
  n = 330941 
  X=0, Y = 65.00 +/- 21.30 
  Weighted least-squares fit:  Y = 71.1 + 1.588 X  + -0.01872 X**2 

slope versus dZ, curvature < 5
  n = 152945 

  Weighted least-squares fit:  Y = 7.2 + 0.332 X  + 0.00292 X**2 
     at X = 100, Y = 69.5 
     effective RMSE xy = 108.6 

slope versus dZ, curvature < 15
  n = 270741 

  Weighted least-squares fit:  Y = 8.1 + 0.304 X  + 0.00285 X**2 

curvature versus dZ, slope < 10
  n = 962 
  X=0, Y = 9.48 +/- 6.06 
  Weighted least-squares fit:  Y = 9.4 + 0.882 X  + 0.32897 X**2 


Number of samples 332823
Max dz = 900
Mean dz = 39
RMS dz = 51.3711981562
100cm = 96.7880825544 percentile value of dz