curvature versus slope
  n = 82440 
  X=0, Y = 24.50 +/- 19.78 
  Weighted least-squares fit:  Y = 58.0 + 1.924 X  + -0.02058 X**2 

slope versus dZ, curvature < 5
  n = 8194 

  Weighted least-squares fit:  Y = 7.8 + 0.212 X  + 0.00335 X**2 
     at X = 100, Y = 62.6 
     effective RMSE xy = 97.5 

slope versus dZ, curvature < 15
  n = 14938 

  Weighted least-squares fit:  Y = 8.5 + 0.160 X  + 0.00555 X**2 

curvature versus dZ, slope < 10
  n = 4901 
  X=0, Y = 9.02 +/- 5.06 
  Weighted least-squares fit:  Y = 8.4 + 1.324 X  + -0.03491 X**2 


Number of samples 83466
Max dz = 900
Mean dz = 89
RMS dz = 138.220837792
100cm = 67.6994225193 percentile value of dz