curvature versus slope
  n = 938247 
  X=0, Y = 54.84 +/- 18.68 
  Weighted least-squares fit:  Y = 61.1 + 1.869 X  + -0.02084 X**2 

slope versus dZ, curvature < 5
  n = 194935 

  Weighted least-squares fit:  Y = 22.4 + -0.109 X  + 0.00479 X**2 
     at X = 100, Y = 59.3 
     effective RMSE xy = 86.3 

slope versus dZ, curvature < 15
  n = 449709 

  Weighted least-squares fit:  Y = 23.1 + -0.068 X  + 0.00488 X**2 

curvature versus dZ, slope < 10
  n = 1610 
  X=0, Y = 17.24 +/- 9.51 
  Weighted least-squares fit:  Y = 17.0 + 1.463 X  + 0.04882 X**2 


Number of samples 948797
Max dz = 900
Mean dz = 46
RMS dz = 70.0571195525
100cm = 89.4649751211 percentile value of dz