curvature versus slope
  n = 1304858 
  X=0, Y = 32.50 +/- 22.38 
  Weighted least-squares fit:  Y = 32.3 + 1.558 X  + -0.01255 X**2 

slope versus dZ, curvature < 5
  n = 9660 

  Weighted least-squares fit:  Y = 3.7 + 0.048 X  + 0.00161 X**2 
     at X = 100, Y = 24.6 
     effective RMSE xy = 38.2 

slope versus dZ, curvature < 15
  n = 45531 

  Weighted least-squares fit:  Y = 3.8 + 0.042 X  + 0.00187 X**2 

curvature versus dZ, slope < 10
  n = 65517 
  X=0, Y = 4.49 +/- 2.38 
  Weighted least-squares fit:  Y = 3.9 + 0.118 X  + 0.00205 X**2 


Number of samples 1308973
Max dz = 900
Mean dz = 16
RMS dz = 24.7184141886
100cm = 99.6164168398 percentile value of dz
Mean dz (curv<=5) = 5
RMS dz (curv<=5) = 8.77496438739