curvature versus slope
  n = 650174 
  X=0, Y = 8.37 +/- 5.84 
  Weighted least-squares fit:  Y = 7.2 + 4.824 X  + -0.05480 X**2 

slope versus dZ, curvature < 5
  n = 409298 
  X=0, Y = 7.17 +/- 4.97 
  Weighted least-squares fit:  Y = 5.8 + 0.304 X  + -0.00097 X**2 
     at X = 100, Y = 26.5 
     effective RMSE xy = 40.7 

slope versus dZ, curvature < 15
  n = 586974 
  X=0, Y = 7.07 +/- 4.75 
  Weighted least-squares fit:  Y = 6.4 + 0.307 X  + 0.00001 X**2 

curvature versus dZ, slope < 10
  n = 513395 
  X=0, Y = 7.27 +/- 4.90 
  Weighted least-squares fit:  Y = 6.5 + 1.546 X  + 0.01976 X**2 


Number of samples 654612
Max dz = 900
Mean dz = 9
RMS dz = 22.427661492
100cm = 99.2569644308 percentile value of dz