curvature versus slope
  n = 1057817 
  X=0, Y = 5.62 +/- 4.45 
  Weighted least-squares fit:  Y = 4.0 + 5.506 X  + -0.08257 X**2 

slope versus dZ, curvature < 5
  n = 741509 
  X=0, Y = 7.46 +/- 6.46 
  Weighted least-squares fit:  Y = 8.1 + 0.341 X  + -0.00045 X**2 
     at X = 100, Y = 37.6 
     effective RMSE xy = 57.7 

slope versus dZ, curvature < 15
  n = 985361 
  X=0, Y = 7.79 +/- 6.64 
  Weighted least-squares fit:  Y = 8.6 + 0.383 X  + -0.00079 X**2 

curvature versus dZ, slope < 10
  n = 872347 
  X=0, Y = 8.40 +/- 6.12 
  Weighted least-squares fit:  Y = 8.1 + 2.329 X  + -0.06215 X**2 


Number of samples 1058572
Max dz = 700
Mean dz = 9
RMS dz = 13.1148770486
100cm = 99.9180972102 percentile value of dz