curvature versus slope
  n = 80764 
  X=0, Y = 22.48 +/- 17.11 
  Weighted least-squares fit:  Y = 41.2 + 2.797 X  + -0.03166 X**2 

slope versus dZ, curvature < 5
  n = 16548 

  Weighted least-squares fit:  Y = 10.4 + 0.207 X  + 0.00284 X**2 
     at X = 100, Y = 59.5 
     effective RMSE xy = 92.0 

slope versus dZ, curvature < 15
  n = 30701 

  Weighted least-squares fit:  Y = 10.5 + 0.304 X  + 0.00217 X**2 

curvature versus dZ, slope < 10
  n = 8320 
  X=0, Y = 12.51 +/- 8.19 
  Weighted least-squares fit:  Y = 11.6 + 2.510 X  + -0.07365 X**2 


Number of samples 81329
Max dz = 800
Mean dz = 39
RMS dz = 74.5318723769
100cm = 91.0241119404 percentile value of dz