curvature versus slope
  n = 375592 
  X=0, Y = 32.44 +/- 26.13 
  Weighted least-squares fit:  Y = 72.9 + 1.318 X  + -0.01404 X**2 

slope versus dZ, curvature < 5
  n = 14028 

  Weighted least-squares fit:  Y = 19.2 + 0.525 X  + 0.00317 X**2 
     at X = 100, Y = 103.3 
     effective RMSE xy = 159.5 

slope versus dZ, curvature < 15
  n = 40360 

  Weighted least-squares fit:  Y = 18.7 + 0.661 X  + 0.00237 X**2 

curvature versus dZ, slope < 10
  n = 5580 
  X=0, Y = 23.76 +/- 11.84 
  Weighted least-squares fit:  Y = 23.9 + 0.864 X  + 0.10353 X**2 


Number of samples 378932
Max dz = 900
Mean dz = 97
RMS dz = 142.877569968
100cm = 63.1408801579 percentile value of dz