curvature versus slope
  n = 207908 
  X=0, Y = 31.95 +/- 24.88 
  Weighted least-squares fit:  Y = 60.6 + 1.926 X  + -0.02101 X**2 

slope versus dZ, curvature < 5
  n = 20263 

  Weighted least-squares fit:  Y = 18.8 + 0.606 X  + 0.00217 X**2 
     at X = 100, Y = 101.1 
     effective RMSE xy = 156.0 

slope versus dZ, curvature < 15
  n = 42644 

  Weighted least-squares fit:  Y = 19.1 + 0.664 X  + 0.00203 X**2 

curvature versus dZ, slope < 10
  n = 8050 
  X=0, Y = 22.69 +/- 12.65 
  Weighted least-squares fit:  Y = 22.7 + 1.734 X  + 0.01169 X**2 


Number of samples 210629
Max dz = 900
Mean dz = 98
RMS dz = 152.826699238
100cm = 65.7397604318 percentile value of dz