curvature versus slope
  n = 144666 
  X=0, Y = 16.88 +/- 14.32 
  Weighted least-squares fit:  Y = 26.7 + 3.908 X  + -0.04706 X**2 

slope versus dZ, curvature < 5
  n = 91948 
  X=0, Y = 10.13 +/- 7.20 
  Weighted least-squares fit:  Y = 7.5 + 0.984 X  + -0.00393 X**2 
     at X = 100, Y = 66.6 
     effective RMSE xy = 104.0 

slope versus dZ, curvature < 15
  n = 110033 
  X=0, Y = 10.13 +/- 7.20 
  Weighted least-squares fit:  Y = 7.1 + 1.173 X  + -0.00517 X**2 

curvature versus dZ, slope < 10
  n = 67657 
  X=0, Y = 11.10 +/- 6.37 
  Weighted least-squares fit:  Y = 10.1 + 3.917 X  + 0.00629 X**2 


Number of samples 146300
Max dz = 900
Mean dz = 30
RMS dz = 81.3510909577
100cm = 92.9480519481 percentile value of dz
Mean dz (curv<=5) = 14
RMS dz (curv<=5) = 38.0