curvature versus slope
  n = 30281 
  X=0, Y = 41.98 +/- 31.00 
  Weighted least-squares fit:  Y = 68.8 + 1.403 X  + -0.01468 X**2 

slope versus dZ, curvature < 5
  n = 2167 

  Weighted least-squares fit:  Y = 12.3 + 0.672 X  + 0.00486 X**2 
     at X = 100, Y = 128.1 
     effective RMSE xy = 200.3 

slope versus dZ, curvature < 15
  n = 5407 

  Weighted least-squares fit:  Y = 12.1 + 0.718 X  + 0.00672 X**2 

curvature versus dZ, slope < 10
  n = 570 
  X=0, Y = 18.93 +/- 11.77 
  Weighted least-squares fit:  Y = 17.9 + 3.134 X  + 0.02271 X**2 


Number of samples 30687
Max dz = 900
Mean dz = 148
RMS dz = 272.069843974
100cm = 55.7336983087 percentile value of dz