curvature versus slope
  n = 264139 
  X=0, Y = 42.23 +/- 25.85 
  Weighted least-squares fit:  Y = 52.6 + 2.276 X  + -0.02473 X**2 

slope versus dZ, curvature < 5
  n = 52871 

  Weighted least-squares fit:  Y = 43.0 + -0.562 X  + 0.00755 X**2 
     at X = 100, Y = 62.3 
     effective RMSE xy = 70.8 

slope versus dZ, curvature < 15
  n = 134646 

  Weighted least-squares fit:  Y = 43.9 + -0.496 X  + 0.00706 X**2 

curvature versus dZ, slope < 10
  n = 9040 
  X=0, Y = 37.30 +/- 18.51 
  Weighted least-squares fit:  Y = 39.4 + 1.001 X  + -0.07502 X**2 


Number of samples 271461
Max dz = 900
Mean dz = 55
RMS dz = 93.5414346693
100cm = 87.066282081 percentile value of dz