curvature versus slope
  n = 524390 
  X=0, Y = 16.02 +/- 10.86 
  Weighted least-squares fit:  Y = 21.0 + 4.093 X  + -0.04688 X**2 

slope versus dZ, curvature < 5
  n = 203968 
  X=0, Y = 14.25 +/- 9.05 
  Weighted least-squares fit:  Y = 7.8 + 0.431 X  + 0.00151 X**2 
     at X = 100, Y = 66.0 
     effective RMSE xy = 103.0 

slope versus dZ, curvature < 15
  n = 359596 
  X=0, Y = 12.19 +/- 8.30 
  Weighted least-squares fit:  Y = 8.5 + 0.476 X  + 0.00122 X**2 

curvature versus dZ, slope < 10
  n = 156742 
  X=0, Y = 10.39 +/- 6.94 
  Weighted least-squares fit:  Y = 9.7 + 2.008 X  + 0.07338 X**2 


Number of samples 534459
Max dz = 900
Mean dz = 26
RMS dz = 53.944415837
100cm = 94.8692041859 percentile value of dz