curvature versus slope
  n = 310845 
  X=0, Y = 12.58 +/- 11.61 
  Weighted least-squares fit:  Y = 26.7 + 3.939 X  + -0.04601 X**2 

slope versus dZ, curvature < 5
  n = 161567 
  X=0, Y = 15.95 +/- 10.40 
  Weighted least-squares fit:  Y = 19.1 + 0.711 X  + 0.00124 X**2 
     at X = 100, Y = 102.6 
     effective RMSE xy = 158.3 

slope versus dZ, curvature < 15
  n = 203139 
  X=0, Y = 15.86 +/- 10.42 
  Weighted least-squares fit:  Y = 18.9 + 0.761 X  + 0.00087 X**2 

curvature versus dZ, slope < 10
  n = 138663 
  X=0, Y = 21.53 +/- 14.54 
  Weighted least-squares fit:  Y = 21.6 + 2.227 X  + 0.02718 X**2 


Number of samples 314922
Max dz = 900
Mean dz = 49
RMS dz = 102.215458713
100cm = 88.0202081785 percentile value of dz
Mean dz (curv<=5) = 21
RMS dz (curv<=5) = 33.7342555869