curvature versus slope
  n = 3621397 
  X=0, Y = 37.10 +/- 28.83 
  Weighted least-squares fit:  Y = 38.4 + 1.518 X  + -0.01294 X**2 

slope versus dZ, curvature < 5
  n = 34507 
  X=0, Y = 1.58 +/- 0.58 
  Weighted least-squares fit:  Y = 3.8 + 0.111 X  + 0.00020 X**2 
     at X = 100, Y = 17.0 
     effective RMSE xy = 26.0 

slope versus dZ, curvature < 15
  n = 207686 
  X=0, Y = 2.70 +/- 2.03 
  Weighted least-squares fit:  Y = 4.1 + 0.111 X  + 0.00063 X**2 

curvature versus dZ, slope < 10
  n = 348481 
  X=0, Y = 4.73 +/- 2.99 
  Weighted least-squares fit:  Y = 4.5 + 0.131 X  + -0.00136 X**2 


Number of samples 3621439
Max dz = 900
Mean dz = 6516
RMS dz = 11998.7273909
100cm = 99.8728406029 percentile value of dz
Mean dz (curv<=5) = 947
RMS dz (curv<=5) = 4648.75563995