curvature versus slope
  n = 290624 
  X=0, Y = 17.94 +/- 14.40 
  Weighted least-squares fit:  Y = 33.6 + 3.431 X  + -0.03842 X**2 

slope versus dZ, curvature < 5
  n = 66568 
  X=0, Y = 54.42 +/- 11.05 
  Weighted least-squares fit:  Y = 38.6 + 0.099 X  + 0.00284 X**2 
     at X = 100, Y = 76.9 
     effective RMSE xy = 104.5 

slope versus dZ, curvature < 15
  n = 117035 
  X=0, Y = 54.42 +/- 11.05 
  Weighted least-squares fit:  Y = 37.0 + 0.231 X  + 0.00251 X**2 

curvature versus dZ, slope < 10
  n = 54810 
  X=0, Y = 41.84 +/- 17.52 
  Weighted least-squares fit:  Y = 38.0 + 0.810 X  + -0.03885 X**2 


Number of samples 299450
Max dz = 900
Mean dz = 66
RMS dz = 98.9545350148
100cm = 81.1200534313 percentile value of dz