curvature versus slope
  n = 536497 
  X=0, Y = 28.04 +/- 21.92 
  Weighted least-squares fit:  Y = 54.2 + 2.033 X  + -0.02047 X**2 

slope versus dZ, curvature < 5
  n = 17099 

  Weighted least-squares fit:  Y = 9.2 + 0.093 X  + 0.00062 X**2 
     at X = 100, Y = 24.7 
     effective RMSE xy = 36.0 

slope versus dZ, curvature < 15
  n = 51867 

  Weighted least-squares fit:  Y = 9.6 + 0.116 X  + 0.00159 X**2 

curvature versus dZ, slope < 10
  n = 8701 
  X=0, Y = 9.90 +/- 5.78 
  Weighted least-squares fit:  Y = 7.9 + 1.986 X  + -0.07651 X**2 


Number of samples 549120
Max dz = 800
Mean dz = 58
RMS dz = 88.6453608487
100cm = 80.8151223776 percentile value of dz