curvature versus slope
  n = 181940 
  X=0, Y = 48.99 +/- 19.91 
  Weighted least-squares fit:  Y = 58.0 + 2.158 X  + -0.02430 X**2 

slope versus dZ, curvature < 5
  n = 106924 

  Weighted least-squares fit:  Y = 7.9 + 0.020 X  + 0.00600 X**2 
     at X = 100, Y = 69.9 
     effective RMSE xy = 109.1 

slope versus dZ, curvature < 15
  n = 149635 

  Weighted least-squares fit:  Y = 7.8 + 0.071 X  + 0.00521 X**2 

curvature versus dZ, slope < 10
  n = 315 
  X=0, Y = 22.40 +/- 12.33 
  Weighted least-squares fit:  Y = 22.0 + 2.734 X  + -1.30375 X**2 


Number of samples 182886
Max dz = 900
Mean dz = 29
RMS dz = 74.6726188104
100cm = 97.3978325296 percentile value of dz