curvature versus slope
  n = 22841 
  X=0, Y = 47.05 +/- 31.05 
  Weighted least-squares fit:  Y = 65.8 + 1.608 X  + -0.01971 X**2 

slope versus dZ, curvature < 5
  n = 4168 

  Weighted least-squares fit:  Y = 17.6 + 0.482 X  + 0.00001 X**2 
     at X = 100, Y = 65.9 
     effective RMSE xy = 99.8 

slope versus dZ, curvature < 15
  n = 10257 

  Weighted least-squares fit:  Y = 18.1 + 0.492 X  + 0.00036 X**2 

curvature versus dZ, slope < 10
  n = 609 
  X=0, Y = 16.87 +/- 13.98 
  Weighted least-squares fit:  Y = 18.4 + 3.920 X  + -0.28611 X**2 


Number of samples 23360
Max dz = 800
Mean dz = 59
RMS dz = 85.6504524215
100cm = 84.2080479452 percentile value of dz