curvature versus slope
  n = 280655 
  X=0, Y = 11.14 +/- 7.82 
  Weighted least-squares fit:  Y = 11.2 + 4.774 X  + -0.05371 X**2 

slope versus dZ, curvature < 5
  n = 155247 
  X=0, Y = 8.22 +/- 5.16 
  Weighted least-squares fit:  Y = 9.5 + 0.237 X  + 0.00147 X**2 
     at X = 100, Y = 47.9 
     effective RMSE xy = 73.7 

slope versus dZ, curvature < 15
  n = 240462 
  X=0, Y = 8.38 +/- 4.53 
  Weighted least-squares fit:  Y = 9.4 + 0.349 X  + 0.00048 X**2 

curvature versus dZ, slope < 10
  n = 177859 
  X=0, Y = 10.62 +/- 6.21 
  Weighted least-squares fit:  Y = 10.2 + 1.064 X  + 0.18887 X**2 


Number of samples 284148
Max dz = 900
Mean dz = 15
RMS dz = 26.6082693913
100cm = 98.6362740544 percentile value of dz