curvature versus slope
  n = 534928 
  X=0, Y = 36.94 +/- 21.84 
  Weighted least-squares fit:  Y = 42.5 + 2.368 X  + -0.02379 X**2 

slope versus dZ, curvature < 5
  n = 112357 

  Weighted least-squares fit:  Y = 5.9 + 0.389 X  + 0.00279 X**2 
     at X = 100, Y = 72.7 
     effective RMSE xy = 113.8 

slope versus dZ, curvature < 15
  n = 294955 

  Weighted least-squares fit:  Y = 7.2 + 0.366 X  + 0.00301 X**2 

curvature versus dZ, slope < 10
  n = 24580 
  X=0, Y = 8.18 +/- 5.39 
  Weighted least-squares fit:  Y = 7.3 + 2.200 X  + -0.01148 X**2 


Number of samples 544717
Max dz = 900
Mean dz = 33
RMS dz = 59.6992462264
100cm = 93.7398685923 percentile value of dz