curvature versus slope
  n = 296716 
  X=0, Y = 10.35 +/- 5.46 
  Weighted least-squares fit:  Y = 8.7 + 4.621 X  + -0.05087 X**2 

slope versus dZ, curvature < 5
  n = 206606 
  X=0, Y = 7.65 +/- 5.37 
  Weighted least-squares fit:  Y = 8.8 + -0.003 X  + 0.00328 X**2 
     at X = 100, Y = 41.3 
     effective RMSE xy = 63.4 

slope versus dZ, curvature < 15
  n = 274748 
  X=0, Y = 7.80 +/- 5.48 
  Weighted least-squares fit:  Y = 8.1 + 0.144 X  + 0.00289 X**2 

curvature versus dZ, slope < 10
  n = 185292 
  X=0, Y = 8.17 +/- 5.53 
  Weighted least-squares fit:  Y = 7.6 + 1.161 X  + 0.06782 X**2 


Number of samples 297833
Max dz = 900
Mean dz = 12
RMS dz = 64.4670458451
100cm = 98.8987116941 percentile value of dz