curvature versus slope
  n = 830403 
  X=0, Y = 4.70 +/- 2.66 
  Weighted least-squares fit:  Y = 2.1 + 5.700 X  + -0.08517 X**2 

slope versus dZ, curvature < 5
  n = 659385 
  X=0, Y = 7.19 +/- 4.36 
  Weighted least-squares fit:  Y = 5.8 + 0.365 X  + 0.00021 X**2 
     at X = 100, Y = 44.4 
     effective RMSE xy = 69.1 

slope versus dZ, curvature < 15
  n = 803604 
  X=0, Y = 7.29 +/- 4.48 
  Weighted least-squares fit:  Y = 6.0 + 0.446 X  + -0.00091 X**2 

curvature versus dZ, slope < 10
  n = 781865 
  X=0, Y = 6.80 +/- 4.19 
  Weighted least-squares fit:  Y = 6.5 + 1.080 X  + 0.15573 X**2 


Number of samples 831210
Max dz = 800
Mean dz = 7
RMS dz = 11.5758369028
100cm = 99.8887164495 percentile value of dz