curvature versus slope
  n = 465909 
  X=0, Y = 17.21 +/- 12.54 
  Weighted least-squares fit:  Y = 30.7 + 3.500 X  + -0.03967 X**2 

slope versus dZ, curvature < 5
  n = 137203 
  X=0, Y = 11.26 +/- 8.68 
  Weighted least-squares fit:  Y = 6.2 + 0.449 X  + 0.00235 X**2 
     at X = 100, Y = 74.6 
     effective RMSE xy = 116.8 

slope versus dZ, curvature < 15
  n = 239471 
  X=0, Y = 10.42 +/- 7.61 
  Weighted least-squares fit:  Y = 6.9 + 0.493 X  + 0.00184 X**2 

curvature versus dZ, slope < 10
  n = 89840 
  X=0, Y = 8.60 +/- 5.47 
  Weighted least-squares fit:  Y = 8.2 + 2.156 X  + 0.04553 X**2 


Number of samples 470977
Max dz = 900
Mean dz = 36
RMS dz = 72.8079665971
100cm = 91.2687880725 percentile value of dz