curvature versus slope
  n = 271919 
  X=0, Y = 56.87 +/- 29.50 
  Weighted least-squares fit:  Y = 73.0 + 1.016 X  + -0.01010 X**2 

slope versus dZ, curvature < 5
  n = 6160 

  Weighted least-squares fit:  Y = 76.3 + 0.492 X  + -0.00220 X**2 
     at X = 100, Y = 103.5 
     effective RMSE xy = 109.9 

slope versus dZ, curvature < 15
  n = 24362 

  Weighted least-squares fit:  Y = 78.9 + 0.330 X  + -0.00042 X**2 

curvature versus dZ, slope < 10
  n = 291 
  X=0, Y = 72.74 +/- 15.99 
  Weighted least-squares fit:  Y = 67.5 + 5.075 X  + -0.16929 X**2 


Number of samples 273151
Max dz = 900
Mean dz = 104
RMS dz = 133.416640641
100cm = 55.270528023 percentile value of dz