curvature versus slope
  n = 1400260 
  X=0, Y = 16.82 +/- 15.67 
  Weighted least-squares fit:  Y = 25.6 + 4.233 X  + -0.04874 X**2 

slope versus dZ, curvature < 5
  n = 620641 
  X=0, Y = 37.51 +/- 27.47 
  Weighted least-squares fit:  Y = 13.8 + 0.733 X  + -0.00487 X**2 
     at X = 100, Y = 38.4 
     effective RMSE xy = 56.3 

slope versus dZ, curvature < 15
  n = 793485 
  X=0, Y = 37.51 +/- 27.47 
  Weighted least-squares fit:  Y = 14.6 + 0.501 X  + -0.00189 X**2 

curvature versus dZ, slope < 10
  n = 604891 
  X=0, Y = 22.53 +/- 17.13 
  Weighted least-squares fit:  Y = 17.2 + 0.047 X  + 0.00080 X**2 


Number of samples 1424957
Max dz = 900
Mean dz = 31
RMS dz = 54.0092584656
100cm = 93.62310582 percentile value of dz