curvature versus slope
  n = 562853 
  X=0, Y = 44.25 +/- 35.62 
  Weighted least-squares fit:  Y = 79.4 + 0.628 X  + -0.00590 X**2 

slope versus dZ, curvature < 5
  n = 7895 

  Weighted least-squares fit:  Y = 11.0 + 0.806 X  + -0.00047 X**2 
     at X = 100, Y = 87.0 
     effective RMSE xy = 135.5 

slope versus dZ, curvature < 15
  n = 28624 

  Weighted least-squares fit:  Y = 10.7 + 1.003 X  + -0.00236 X**2 

curvature versus dZ, slope < 10
  n = 2276 
  X=0, Y = 19.03 +/- 8.74 
  Weighted least-squares fit:  Y = 15.8 + 3.090 X  + -0.00120 X**2 


Number of samples 569562
Max dz = 900
Mean dz = 92
RMS dz = 122.262013725
100cm = 63.6748940414 percentile value of dz