curvature versus slope
  n = 283442 
  X=0, Y = 42.13 +/- 31.17 
  Weighted least-squares fit:  Y = 68.9 + 1.295 X  + -0.01358 X**2 

slope versus dZ, curvature < 5
  n = 20707 

  Weighted least-squares fit:  Y = 8.1 + 0.580 X  + 0.00272 X**2 
     at X = 100, Y = 93.3 
     effective RMSE xy = 146.0 

slope versus dZ, curvature < 15
  n = 55718 

  Weighted least-squares fit:  Y = 7.3 + 0.699 X  + 0.00174 X**2 

curvature versus dZ, slope < 10
  n = 5633 
  X=0, Y = 12.98 +/- 6.93 
  Weighted least-squares fit:  Y = 12.0 + 1.790 X  + 0.03441 X**2 


Number of samples 286132
Max dz = 900
Mean dz = 78
RMS dz = 118.105884697
100cm = 71.8996826639 percentile value of dz