curvature versus slope
  n = 264011 
  X=0, Y = 37.97 +/- 18.89 
  Weighted least-squares fit:  Y = 45.5 + 2.497 X  + -0.02699 X**2 

slope versus dZ, curvature < 5
  n = 52513 

  Weighted least-squares fit:  Y = 37.2 + 0.007 X  + 0.00247 X**2 
     at X = 100, Y = 62.5 
     effective RMSE xy = 79.0 

slope versus dZ, curvature < 15
  n = 126899 

  Weighted least-squares fit:  Y = 39.2 + -0.040 X  + 0.00309 X**2 

curvature versus dZ, slope < 10
  n = 4352 
  X=0, Y = 34.56 +/- 13.18 
  Weighted least-squares fit:  Y = 33.4 + 2.519 X  + -0.13340 X**2 


Number of samples 271720
Max dz = 900
Mean dz = 60
RMS dz = 90.0610903776
100cm = 86.4588547034 percentile value of dz