curvature versus slope
  n = 852718 
  X=0, Y = 5.93 +/- 3.88 
  Weighted least-squares fit:  Y = 2.3 + 4.985 X  + -0.06033 X**2 

slope versus dZ, curvature < 5
  n = 540552 
  X=0, Y = 11.23 +/- 6.37 
  Weighted least-squares fit:  Y = 9.8 + 0.383 X  + -0.00104 X**2 
     at X = 100, Y = 37.7 
     effective RMSE xy = 57.1 

slope versus dZ, curvature < 15
  n = 799527 
  X=0, Y = 11.38 +/- 6.55 
  Weighted least-squares fit:  Y = 10.5 + 0.359 X  + 0.00060 X**2 

curvature versus dZ, slope < 10
  n = 727215 
  X=0, Y = 11.30 +/- 6.76 
  Weighted least-squares fit:  Y = 10.7 + 1.599 X  + 0.01490 X**2 


Number of samples 853620
Max dz = 500
Mean dz = 11
RMS dz = 15.0
100cm = 99.8781659286 percentile value of dz