curvature versus slope
  n = 218613 
  X=0, Y = 74.63 +/- 25.23 
  Weighted least-squares fit:  Y = 79.4 + 0.814 X  + -0.00803 X**2 

slope versus dZ, curvature < 5
  n = 9648 

  Weighted least-squares fit:  Y = 43.9 + 1.052 X  + -0.00442 X**2 
     at X = 100, Y = 104.9 
     effective RMSE xy = 149.7 

slope versus dZ, curvature < 15
  n = 37969 

  Weighted least-squares fit:  Y = 48.1 + 0.917 X  + -0.00259 X**2 

curvature versus dZ, slope < 10
  n = 138 
  X=0, Y = 73.19 +/- 32.98 
  Weighted least-squares fit:  Y = 60.0 + -2.663 X  + 0.43467 X**2 


Number of samples 219629
Max dz = 900
Mean dz = 103
RMS dz = 136.930639376
100cm = 57.25336818 percentile value of dz