curvature versus slope
  n = 287130 
  X=0, Y = 14.41 +/- 9.90 
  Weighted least-squares fit:  Y = 20.9 + 4.099 X  + -0.04695 X**2 

slope versus dZ, curvature < 5
  n = 135943 
  X=0, Y = 13.00 +/- 5.42 
  Weighted least-squares fit:  Y = 9.4 + 0.223 X  + 0.00127 X**2 
     at X = 100, Y = 44.4 
     effective RMSE xy = 68.2 

slope versus dZ, curvature < 15
  n = 193679 
  X=0, Y = 12.08 +/- 5.98 
  Weighted least-squares fit:  Y = 9.3 + 0.259 X  + 0.00124 X**2 

curvature versus dZ, slope < 10
  n = 100628 
  X=0, Y = 11.22 +/- 6.86 
  Weighted least-squares fit:  Y = 10.5 + 0.772 X  + 0.07201 X**2 


Number of samples 290708
Max dz = 900
Mean dz = 20
RMS dz = 45.2437841035
100cm = 97.400140347 percentile value of dz