curvature versus slope
  n = 542711 
  X=0, Y = 18.27 +/- 19.33 
  Weighted least-squares fit:  Y = 71.4 + 1.422 X  + -0.01526 X**2 

slope versus dZ, curvature < 5
  n = 24105 
  X=0, Y = 11.49 +/- 10.25 
  Weighted least-squares fit:  Y = 8.8 + 0.730 X  + 0.00002 X**2 
     at X = 100, Y = 82.0 
     effective RMSE xy = 128.0 

slope versus dZ, curvature < 15
  n = 51169 
  X=0, Y = 11.49 +/- 10.25 
  Weighted least-squares fit:  Y = 8.2 + 0.990 X  + -0.00193 X**2 

curvature versus dZ, slope < 10
  n = 16737 
  X=0, Y = 9.56 +/- 6.70 
  Weighted least-squares fit:  Y = 9.8 + 5.412 X  + -0.01132 X**2 


Number of samples 549636
Max dz = 900
Mean dz = 84
RMS dz = 119.682914403
100cm = 68.5522782351 percentile value of dz