curvature versus slope
  n = 784733 
  X=0, Y = 14.29 +/- 11.83 
  Weighted least-squares fit:  Y = 27.6 + 3.861 X  + -0.04428 X**2 

slope versus dZ, curvature < 5
  n = 330381 
  X=0, Y = 21.45 +/- 12.53 
  Weighted least-squares fit:  Y = 40.6 + 0.042 X  + 0.00195 X**2 
     at X = 100, Y = 64.3 
     effective RMSE xy = 78.3 

slope versus dZ, curvature < 15
  n = 508056 
  X=0, Y = 20.62 +/- 11.92 
  Weighted least-squares fit:  Y = 42.2 + -0.050 X  + 0.00348 X**2 

curvature versus dZ, slope < 10
  n = 336678 
  X=0, Y = 38.24 +/- 19.59 
  Weighted least-squares fit:  Y = 40.2 + 1.496 X  + 0.06968 X**2 


Number of samples 796390
Max dz = 900
Mean dz = 53
RMS dz = 80.7960395069
100cm = 89.7774959505 percentile value of dz