curvature versus slope
  n = 9832299 
  X=0, Y = 24.73 +/- 21.67 
  Weighted least-squares fit:  Y = 26.1 + 4.048 X  + -0.04602 X**2 

slope versus dZ, curvature < 5
  n = 2913091 

  Weighted least-squares fit:  Y = 21.9 + 0.269 X  + -0.00074 X**2 
     at X = 100, Y = 41.4 
     effective RMSE xy = 55.2 

slope versus dZ, curvature < 15
  n = 5338385 

  Weighted least-squares fit:  Y = 20.8 + 0.143 X  + 0.00045 X**2 

curvature versus dZ, slope < 10
  n = 2929818 
  X=0, Y = 37.16 +/- 27.47 
  Weighted least-squares fit:  Y = 24.4 + -1.159 X  + 0.02524 X**2 


Number of samples 10004693
Max dz = 900
Mean dz = 25
RMS dz = 38.6264158317
100cm = 97.3644068838 percentile value of dz