curvature versus slope
  n = 317056 
  X=0, Y = 39.81 +/- 27.89 
  Weighted least-squares fit:  Y = 60.1 + 1.865 X  + -0.01887 X**2 

slope versus dZ, curvature < 5
  n = 12612 

  Weighted least-squares fit:  Y = 7.5 + 0.054 X  + 0.00034 X**2 
     at X = 100, Y = 16.3 
     effective RMSE xy = 22.7 

slope versus dZ, curvature < 15
  n = 26566 

  Weighted least-squares fit:  Y = 8.0 + 0.056 X  + 0.00224 X**2 

curvature versus dZ, slope < 10
  n = 3312 
  X=0, Y = 8.07 +/- 5.34 
  Weighted least-squares fit:  Y = 8.4 + -0.428 X  + 0.24521 X**2 


Number of samples 325284
Max dz = 900
Mean dz = 65
RMS dz = 94.4298681562
100cm = 77.2549525953 percentile value of dz