curvature versus slope
  n = 176813 
  X=0, Y = 48.09 +/- 35.51 
  Weighted least-squares fit:  Y = 76.3 + 0.839 X  + -0.00822 X**2 

slope versus dZ, curvature < 5
  n = 6338 

  Weighted least-squares fit:  Y = 25.9 + -0.180 X  + 0.00493 X**2 
     at X = 100, Y = 57.3 
     effective RMSE xy = 80.2 

slope versus dZ, curvature < 15
  n = 18856 

  Weighted least-squares fit:  Y = 25.5 + -0.071 X  + 0.00413 X**2 

curvature versus dZ, slope < 10
  n = 2058 
  X=0, Y = 24.99 +/- 8.78 
  Weighted least-squares fit:  Y = 25.6 + -1.423 X  + 0.26610 X**2 


Number of samples 178868
Max dz = 900
Mean dz = 74
RMS dz = 112.231902773
100cm = 74.3285551356 percentile value of dz