curvature versus slope
  n = 1793727 
  X=0, Y = 15.38 +/- 11.93 
  Weighted least-squares fit:  Y = 9.8 + 1.731 X  + -0.01061 X**2 

slope versus dZ, curvature < 5
  n = 39070 

  Weighted least-squares fit:  Y = 4.1 + 0.103 X  + 0.00031 X**2 
     at X = 100, Y = 17.5 
     effective RMSE xy = 26.7 

slope versus dZ, curvature < 15
  n = 160761 
  X=0, Y = 3.08 +/- 2.60 
  Weighted least-squares fit:  Y = 4.1 + 0.065 X  + 0.00143 X**2 

curvature versus dZ, slope < 10
  n = 647428 
  X=0, Y = 5.23 +/- 3.33 
  Weighted least-squares fit:  Y = 4.4 + 0.030 X  + 0.00322 X**2 


Number of samples 1797221
Max dz = 900
Mean dz = 9
RMS dz = 22.7815714998
100cm = 99.7858360213 percentile value of dz
Mean dz (curv<=5) = 4
RMS dz (curv<=5) = 9.64365076099