curvature versus slope
  n = 156269 
  X=0, Y = 42.25 +/- 13.63 
  Weighted least-squares fit:  Y = 53.6 + 2.140 X  + -0.02315 X**2 

slope versus dZ, curvature < 5
  n = 48404 

  Weighted least-squares fit:  Y = 79.0 + 0.114 X  + -0.00003 X**2 
     at X = 100, Y = 90.2 
     effective RMSE xy = 68.3 

slope versus dZ, curvature < 15
  n = 80361 

  Weighted least-squares fit:  Y = 81.6 + -0.001 X  + 0.00116 X**2 

curvature versus dZ, slope < 10
  n = 161 
  X=0, Y = 62.51 +/- 14.59 
  Weighted least-squares fit:  Y = 59.4 + 7.233 X  + -0.79399 X**2 


Number of samples 157976
Max dz = 900
Mean dz = 92
RMS dz = 118.574870862
100cm = 72.1039904796 percentile value of dz