curvature versus slope
  n = 290760 
  X=0, Y = 23.61 +/- 17.94 
  Weighted least-squares fit:  Y = 46.8 + 2.417 X  + -0.02652 X**2 

slope versus dZ, curvature < 5
  n = 38843 

  Weighted least-squares fit:  Y = 5.3 + 0.499 X  + 0.00225 X**2 
     at X = 100, Y = 77.6 
     effective RMSE xy = 121.7 

slope versus dZ, curvature < 15
  n = 81454 

  Weighted least-squares fit:  Y = 5.4 + 0.585 X  + 0.00166 X**2 

curvature versus dZ, slope < 10
  n = 22540 
  X=0, Y = 8.60 +/- 5.19 
  Weighted least-squares fit:  Y = 6.5 + 3.183 X  + -0.09374 X**2 


Number of samples 292583
Max dz = 900
Mean dz = 60
RMS dz = 100.359354322
100cm = 79.8296551748 percentile value of dz