curvature versus slope
  n = 1036570 
  X=0, Y = 18.83 +/- 14.52 
  Weighted least-squares fit:  Y = 59.8 + 2.062 X  + -0.02172 X**2 

slope versus dZ, curvature < 5
  n = 30369 

  Weighted least-squares fit:  Y = 16.6 + 0.231 X  + -0.00073 X**2 
     at X = 100, Y = 32.4 
     effective RMSE xy = 43.7 

slope versus dZ, curvature < 15
  n = 71985 

  Weighted least-squares fit:  Y = 18.9 + 0.184 X  + 0.00171 X**2 

curvature versus dZ, slope < 10
  n = 18951 
  X=0, Y = 18.28 +/- 11.09 
  Weighted least-squares fit:  Y = 16.6 + 3.620 X  + -0.28794 X**2 


Number of samples 1057204
Max dz = 700
Mean dz = 66
RMS dz = 91.5478017213
100cm = 77.3298247074 percentile value of dz