curvature versus slope
  n = 84590 
  X=0, Y = 20.88 +/- 16.02 
  Weighted least-squares fit:  Y = 38.1 + 2.956 X  + -0.03301 X**2 

slope versus dZ, curvature < 5
  n = 16054 

  Weighted least-squares fit:  Y = 16.9 + 0.353 X  + 0.00073 X**2 
     at X = 100, Y = 59.5 
     effective RMSE xy = 89.6 

slope versus dZ, curvature < 15
  n = 31105 

  Weighted least-squares fit:  Y = 15.9 + 0.456 X  + 0.00101 X**2 

curvature versus dZ, slope < 10
  n = 10338 
  X=0, Y = 18.36 +/- 5.22 
  Weighted least-squares fit:  Y = 18.3 + 0.099 X  + 0.12171 X**2 


Number of samples 85657
Max dz = 900
Mean dz = 50
RMS dz = 96.5038859321
100cm = 86.039669846 percentile value of dz