curvature versus slope
  n = 533933 
  X=0, Y = 49.63 +/- 25.32 
  Weighted least-squares fit:  Y = 60.2 + 1.599 X  + -0.01617 X**2 

slope versus dZ, curvature < 5
  n = 32541 

  Weighted least-squares fit:  Y = 94.0 + 0.665 X  + -0.00154 X**2 
     at X = 100, Y = 145.1 
     effective RMSE xy = 173.6 

slope versus dZ, curvature < 15
  n = 138584 

  Weighted least-squares fit:  Y = 94.9 + 0.604 X  + -0.00115 X**2 

curvature versus dZ, slope < 10
  n = 1656 
  X=0, Y = 103.09 +/- 54.35 
  Weighted least-squares fit:  Y = 96.0 + 4.284 X  + -0.19664 X**2 


Number of samples 535047
Max dz = 900
Mean dz = 117
RMS dz = 139.653141748
100cm = 38.2704696971 percentile value of dz
Mean dz (curv<=5) = 108
RMS dz (curv<=5) = 122.057363563