curvature versus slope
  n = 222108 
  X=0, Y = 62.14 +/- 25.26 
  Weighted least-squares fit:  Y = 59.8 + 0.610 X  + -0.00388 X**2 

slope versus dZ, curvature < 5
  n = 453 

  Weighted least-squares fit:  Y = -10.8 + 0.887 X  + -0.00624 X**2 
     at X = 100, Y = 15.5 
     effective RMSE xy = 17.6 

slope versus dZ, curvature < 15
  n = 3412 

  Weighted least-squares fit:  Y = -6.6 + 0.739 X  + -0.00456 X**2 

curvature versus dZ, slope < 10
  n = 362 

  Weighted least-squares fit:  Y = 2.8 + 0.227 X  + -0.00114 X**2 


Number of samples 223623
Max dz = 900
Mean dz = 4431
RMS dz = 8930.47070428
100cm = 99.6078220934 percentile value of dz
Mean dz (curv<=5) = 1675
RMS dz (curv<=5) = 6434.05160066