curvature versus slope
  n = 602868 
  X=0, Y = 7.95 +/- 6.69 
  Weighted least-squares fit:  Y = 14.0 + 4.336 X  + -0.06912 X**2 

slope versus dZ, curvature < 5
  n = 323852 
  X=0, Y = 5.82 +/- 3.56 
  Weighted least-squares fit:  Y = 4.1 + 0.361 X  + 0.00081 X**2 
     at X = 100, Y = 48.3 
     effective RMSE xy = 75.6 

slope versus dZ, curvature < 15
  n = 396075 
  X=0, Y = 5.90 +/- 3.60 
  Weighted least-squares fit:  Y = 4.0 + 0.440 X  + 0.00012 X**2 

curvature versus dZ, slope < 10
  n = 339950 
  X=0, Y = 5.42 +/- 3.45 
  Weighted least-squares fit:  Y = 3.5 + 2.966 X  + -0.01668 X**2 


Number of samples 619359
Max dz = 800
Mean dz = 17
RMS dz = 33.5410196625
100cm = 96.9431299133 percentile value of dz