curvature versus slope
  n = 492376 
  X=0, Y = 6.81 +/- 5.21 
  Weighted least-squares fit:  Y = 5.1 + 5.360 X  + -0.06377 X**2 

slope versus dZ, curvature < 5
  n = 354586 
  X=0, Y = 9.57 +/- 5.80 
  Weighted least-squares fit:  Y = 8.4 + 0.244 X  + -0.00007 X**2 
     at X = 100, Y = 32.2 
     effective RMSE xy = 48.7 

slope versus dZ, curvature < 15
  n = 456776 
  X=0, Y = 9.77 +/- 6.05 
  Weighted least-squares fit:  Y = 8.7 + 0.231 X  + 0.00098 X**2 

curvature versus dZ, slope < 10
  n = 422514 
  X=0, Y = 9.36 +/- 5.49 
  Weighted least-squares fit:  Y = 8.9 + 0.790 X  + 0.08350 X**2 


Number of samples 494146
Max dz = 900
Mean dz = 9
RMS dz = 16.3707055437
100cm = 99.6037608318 percentile value of dz