curvature versus slope
  n = 4573445 
  X=0, Y = 26.25 +/- 23.39 
  Weighted least-squares fit:  Y = 34.2 + 1.586 X  + -0.01281 X**2 

slope versus dZ, curvature < 5
  n = 131667 
  X=0, Y = 4.71 +/- 1.92 
  Weighted least-squares fit:  Y = 2.9 + 0.193 X  + 0.00042 X**2 
     at X = 100, Y = 26.4 
     effective RMSE xy = 41.2 

slope versus dZ, curvature < 15
  n = 593128 
  X=0, Y = 4.40 +/- 1.91 
  Weighted least-squares fit:  Y = 2.7 + 0.219 X  + 0.00028 X**2 

curvature versus dZ, slope < 10
  n = 843428 
  X=0, Y = 4.14 +/- 2.12 
  Weighted least-squares fit:  Y = 3.4 + 0.195 X  + -0.00153 X**2 


Number of samples 4691251
Max dz = 900
Mean dz = 1063
RMS dz = 5007.03475123
100cm = 99.9028830476 percentile value of dz
Mean dz (curv<=5) = 81
RMS dz (curv<=5) = 1376.46939668