curvature versus slope
  n = 431218 
  X=0, Y = 28.21 +/- 18.32 
  Weighted least-squares fit:  Y = 48.4 + 2.505 X  + -0.02791 X**2 

slope versus dZ, curvature < 5
  n = 62650 
  X=0, Y = 20.26 +/- 7.85 
  Weighted least-squares fit:  Y = 31.5 + 0.078 X  + 0.00228 X**2 
     at X = 100, Y = 62.1 
     effective RMSE xy = 84.1 

slope versus dZ, curvature < 15
  n = 141660 
  X=0, Y = 27.94 +/- 12.75 
  Weighted least-squares fit:  Y = 31.7 + 0.065 X  + 0.00281 X**2 

curvature versus dZ, slope < 10
  n = 19375 
  X=0, Y = 33.20 +/- 10.07 
  Weighted least-squares fit:  Y = 31.6 + 0.705 X  + 0.00850 X**2 


Number of samples 443102
Max dz = 900
Mean dz = 64
RMS dz = 93.4130611853
100cm = 80.7599604606 percentile value of dz