curvature versus slope
  n = 246482 
  X=0, Y = 54.05 +/- 28.31 
  Weighted least-squares fit:  Y = 72.9 + 1.120 X  + -0.01200 X**2 

slope versus dZ, curvature < 5
  n = 30108 

  Weighted least-squares fit:  Y = 92.4 + 0.721 X  + -0.00133 X**2 
     at X = 100, Y = 151.3 
     effective RMSE xy = 188.1 

slope versus dZ, curvature < 15
  n = 63415 

  Weighted least-squares fit:  Y = 93.1 + 0.709 X  + -0.00100 X**2 

curvature versus dZ, slope < 10
  n = 2008 
  X=0, Y = 100.88 +/- 12.89 
  Weighted least-squares fit:  Y = 99.0 + 2.574 X  + 0.04687 X**2 


Number of samples 247766
Max dz = 900
Mean dz = 148
RMS dz = 176.951970885
100cm = 28.5745421083 percentile value of dz