curvature versus slope
  n = 203500 
  X=0, Y = 11.48 +/- 9.17 
  Weighted least-squares fit:  Y = 18.5 + 3.855 X  + -0.04230 X**2 

slope versus dZ, curvature < 5
  n = 86463 
  X=0, Y = 9.43 +/- 5.88 
  Weighted least-squares fit:  Y = 8.7 + 0.317 X  + -0.00012 X**2 
     at X = 100, Y = 39.2 
     effective RMSE xy = 60.1 

slope versus dZ, curvature < 15
  n = 127221 
  X=0, Y = 9.01 +/- 5.57 
  Weighted least-squares fit:  Y = 8.6 + 0.376 X  + -0.00037 X**2 

curvature versus dZ, slope < 10
  n = 92304 
  X=0, Y = 10.28 +/- 6.20 
  Weighted least-squares fit:  Y = 9.6 + 1.103 X  + 0.05990 X**2 


Number of samples 206307
Max dz = 900
Mean dz = 23
RMS dz = 49.8196748283
100cm = 96.4795183876 percentile value of dz