curvature versus slope
  n = 505692 
  X=0, Y = 15.81 +/- 12.77 
  Weighted least-squares fit:  Y = 35.6 + 3.333 X  + -0.03737 X**2 

slope versus dZ, curvature < 5
  n = 113538 
  X=0, Y = 26.64 +/- 4.95 
  Weighted least-squares fit:  Y = 28.2 + 0.320 X  + 0.00309 X**2 
     at X = 100, Y = 91.1 
     effective RMSE xy = 136.2 

slope versus dZ, curvature < 15
  n = 208005 
  X=0, Y = 24.95 +/- 5.47 
  Weighted least-squares fit:  Y = 27.4 + 0.390 X  + 0.00305 X**2 

curvature versus dZ, slope < 10
  n = 102391 
  X=0, Y = 30.09 +/- 12.83 
  Weighted least-squares fit:  Y = 30.7 + -0.017 X  + 0.00887 X**2 


Number of samples 510912
Max dz = 900
Mean dz = 63
RMS dz = 101.754606775
100cm = 81.1272782788 percentile value of dz