curvature versus slope
  n = 119727 
  X=0, Y = 78.21 +/- 33.28 
  Weighted least-squares fit:  Y = 83.5 + 0.596 X  + -0.00568 X**2 

slope versus dZ, curvature < 5
  n = 1098 

  Weighted least-squares fit:  Y = 21.5 + -0.077 X  + 0.00598 X**2 
     at X = 100, Y = 73.6 
     effective RMSE xy = 110.6 

slope versus dZ, curvature < 15
  n = 5832 

  Weighted least-squares fit:  Y = 18.6 + 0.436 X  + 0.00196 X**2 

curvature versus dZ, slope < 10
  n = 36 

  Weighted least-squares fit:  Y = 16.0 + 6.043 X  + -0.31353 X**2 


Number of samples 120790
Max dz = 900
Mean dz = 101
RMS dz = 146.734454032
100cm = 62.3230399868 percentile value of dz