curvature versus slope
  n = 831700 
  X=0, Y = 7.37 +/- 6.02 
  Weighted least-squares fit:  Y = 13.8 + 4.840 X  + -0.05575 X**2 

slope versus dZ, curvature < 5
  n = 572686 
  X=0, Y = 10.24 +/- 5.11 
  Weighted least-squares fit:  Y = 11.1 + 0.387 X  + 0.00008 X**2 
     at X = 100, Y = 50.5 
     effective RMSE xy = 77.4 

slope versus dZ, curvature < 15
  n = 661264 
  X=0, Y = 10.25 +/- 5.11 
  Weighted least-squares fit:  Y = 11.1 + 0.449 X  + -0.00026 X**2 

curvature versus dZ, slope < 10
  n = 562128 
  X=0, Y = 11.58 +/- 6.07 
  Weighted least-squares fit:  Y = 11.5 + 3.051 X  + 0.03496 X**2 


Number of samples 853883
Max dz = 900
Mean dz = 21
RMS dz = 39.0896405714
100cm = 96.4800798236 percentile value of dz